Thomas F. Torrance's model of the stratification of knowledge is one of his most striking and original contributions to theological method. Torrance's model offers an account of the way formal theological knowledge emerges from our intuitive and pre-conceptual grasp of God's reality as it is manifest in Jesus Christ. It presents a vision of theological progression, in which our knowledge moves towards an ever more refined and more unified conceptualisation of the reality of God, while remaining closely coordinated with the concrete level of personal and experiential knowledge of Jesus Christ. According to this model, our thought rises to higher levels of theological conceptualisation only as we penetrate more deeply into the reality of Jesus Christ. From the ground level of personal experience to the highest level of theological reflection, Jesus Christ thus remains central. Through a sustained concentration on him and on his homoousial union with God, we are able to achieve a formal account of the underlying trinitarian structure of God's saving economy and, finally, of the trinitarian relations immanent in God's own eternal being, which constitute the ultimate grammar of all theological discourse.

In the discussion that follows I will first of all sketch the broad outlines of Torrance's realist epistemology, since Torrance's view of the stratified structure of knowledge rests on his basic epistemological position. I will then examine in detail the three levels of Torrance's stratification model, before suggesting some of this model's most significant and most valuable implications for theological method in general.Footnote ¹

The objectivity of knowledge

The ‘quintessence’ of Torrance's scientific approach to theology is, as Alister McGrath has observed, the conviction that every reality must be investigated according to its own nature.Footnote ² For Torrance, all true knowledge is objective knowledge; it is knowledge based on and guided by its object. Objective thinking ‘lays itself open to the nature and reality of the object in order to take its shape from the structure of the object and not to impose upon it a structure of its own prescription’.Footnote ³ Thus, in any field of investigation the object must prescribe the mode of thought which is directed towards it. This kind of respect for objectivity is nothing less than ‘the sine qua non of scientific activity’.Footnote ⁴ According to Torrance, this is the sense in which theological thought is scientific: it is thought devoted to its proper object.Footnote ⁵ And for Torrance the object of theology is ‘God in his Revelation’,Footnote ⁶ or, more simply, ‘Jesus Christ’.Footnote ⁷ The one fundamental presupposition of theology is therefore the ‘utter lordship’ and ‘absolute precedence’ of this particular object.Footnote ⁸

In Torrance's thought, the emphasis on the objectivity of knowledge does not, however, undermine the subjective dimension of knowledge. With Michael Polanyi, Torrance affirms that the primacy of the object does not entail a disinterested approach to knowledge, but rather an intense, personal attachment to the object, and a profound commitment which enables us to distinguish the reality of the object from our own subjectivity.Footnote ⁹ Such an epistemological commitment is itself both personal and objective, for we freely allow our own preconceptions to be challenged and called into question by the object.Footnote ¹⁰ In true knowledge, we are thus simultaneously involved in a movement of increasing openness to the object and in a subjective process of ‘self-renunciation, repentance and change of mind’.Footnote ¹¹ Only by being subjectively adapted to the object in this way can the personal knower become ‘open to real objectivity’, and thus to real knowledge.Footnote ¹²

According to Torrance, theology's objectivity constitutes both its similarity to the other sciences and its difference from them. On the one hand, there is only one basic way of knowing common to all disciplines: ‘we know some given reality strictly in accordance with its nature’.Footnote ¹³ Theology is nevertheless distinct from all other disciplines, for it is devoted to a unique object which demands its own unique forms of thought.Footnote ¹⁴ The integrity of theology as a science in its own right therefore depends on ‘a sustained integration of theological reflection with its proper object and a rigorous development of its own field of rational activity’.Footnote ¹⁵

In view of Torrance's understanding of the objectivity of knowledge, it is clear that only with important qualifications can we describe his epistemology as ‘realist’.Footnote ¹⁶ For Torrance, there is no necessary correlation between knowledge and being; such a correlation obtains only in so far as knowledge unfolds in accordance with the nature of the object.Footnote ¹⁷ In other words, our aim in thinking is to develop a ‘correlation of the intelligible and the intelligent’,Footnote ¹⁸ by allowing all knowledge to be guided and governed by its object, and by allowing the object itself to prescribe the thought-forms which we adopt towards it.Footnote ¹⁹ Thus realism for Torrance involves the free decision to let the intrinsic structure of the object impose itself on our minds.Footnote ²⁰ Objective thinking, then, is always grounded in empirical actuality, and it develops a posteriori from its empirical basis.

In spite of the rigour with which Torrance affirms the objectivity of knowledge, he does not view truth in terms of any simplistic correspondence theory.Footnote ²¹ Even in thinking that is governed by its object, there is never a direct correspondence between thought and reality. Rather, the concepts we develop can only refer away from themselves to a reality which transcends thought.Footnote ²² Theological conceptuality is therefore never equivalent to the ontic structures in reality, but it is at best a ‘disclosure model’ through which reality may make itself known to us.Footnote ²³

A realism such as this will never seek to determine epistemological method in advance of actual knowledge. In theological reflection, the method by which God can be known ‘must be determined from first to last by the way in which he actually is known’,Footnote ²⁴ so that knowledge is not for a moment separated from the nature of the object.Footnote ²⁵ Theological thought is methodologically sound only when it seeks to let our empirical relation to the object determine the thought-forms which we adopt toward it. This determination of method by reality, in which ontology and epistemology ‘unfold together’, has rightly been described as the ‘fundamental axiom’ of Torrance's thought.Footnote ²⁶

At this point we can understand why Torrance lays so great an emphasis on the epistemological significance of both the incarnation and the Nicene homoousion. The incarnation is epistemologically essential because we can know God only ‘in accordance with the way in which he has actually objectified himself for us in our human existence, in Jesus Christ’.Footnote ²⁷ The homoousion signifies the union between God and his self-revelation in Jesus Christ, between the divine being and the divine act, and, consequently, the relation between the divine ontology and our knowledge of God through the gospel.Footnote ²⁸ It ‘crystalises the conviction that while the incarnation falls within the structures of our spatio-temporal humanity in this world, it also falls within the Life and Being of God’, so that in our relation to Jesus Christ we have to do ‘with the ultimate Reality of God’.Footnote ²⁹ For Torrance, the homoousion is thus nothing less than ‘the ontological and epistemological linchpin of Christian theology’.Footnote ³⁰ And it remains, too, at the heart of the model of epistemological stratification which Torrance develops on the basis of his realism.

Torrance's stratification model is not an a priori construction of the formal possibilities of knowing God, but it is itself an attempt to explicate the way theological knowledge unfolds under the influence of its divine object. It is thus a model of the stratified form which our knowledge of God actually takes whenever it is truly objective knowledge.

The stratification of knowledge

Torrance's model of the stratified structure of theological knowledge is deeply indebted to the thought of both Einstein and Polanyi. According to this model, our conceptual knowledge arises from the ground level of our intuitive apprehension of reality; and, even as this knowledge becomes increasingly formalised, it remains closely coordinated with our basic intuitive experience of reality. Thus we advance towards ever more refined conceptuality not by moving away from concrete reality, but by penetrating more deeply into it. In this stratified process of knowing we are therefore progressively ‘grasping reality in its depth’ – which is, for Torrance, the basic function of ‘scientific knowledge’.Footnote ³¹

The first level of theological knowledge in Torrance's model is the level of tacit theology, or, in Torrance's words, the ‘evangelical and doxological level’.Footnote ³² Like Polanyi's tacit dimension, this level involves an ‘informal and undefined’ knowledge grounded in personal experience.Footnote ³³ It is the level of our personal encounter with Jesus Christ, and of ‘our day-to-day worship and meeting with God in response to the proclamation of the Gospel. . . within the fellowship of the Church’.Footnote ³⁴ In encountering Jesus Christ we experience the act of God; it is a threefold act of self-revelation in which God turns towards us as Father, Son and Holy Spirit. Without yet having any explicit knowledge of the triune structure of this saving revelation, we nevertheless grasp intuitively the threefold form of God's action: the grace of the Lord Jesus Christ, the love of God the Father and the fellowship of the Holy Spirit. Under the creative impact of God's self-revelation, the trinitarian pattern of God's being thus becomes ‘imprinted’ on our minds, just as it first became tacitly imprinted on the New Testament witness and on the mind of the early Christian community long before the development of any formalised trinitarian theology.Footnote ³⁵ In this way trinitarian thinking enters ‘into the inner fabric of all our Christian worship and knowledge of the one God’.Footnote ³⁶ Our knowledge at this level precedes and is entirely independent of analytical and logical processes, so that here we mysteriously grasp the triune reality of God ‘at once as a whole’.Footnote ³⁷ And there is no distinction at this level between the empirical and the conceptual: ‘our experiences and cognitions are naturally and inseparably combined’ in such a way that our most basic tacit concepts ‘are directly correlated with the complex of our experience’.Footnote ³⁸

Although this incipient and spontaneous knowledge of God precedes analysis, it is nevertheless the most profound kind of theological knowledge. Just as a child by the age of five is said to have intuitively learned far more about the physical world than even the most brilliant physicist could ever conceptualise, so too ‘we learn far more about God as Father, Son and Holy Spirit. . . within the family and fellowship of the living tradition of the Church than we can ever say: it becomes built into the structure of our souls and minds, and we know much more than we can ever tell’.Footnote ³⁹

When Torrance speaks of the movement to ‘higher’ levels of theological knowledge, there is therefore no question of leaving behind this first level of intuitive knowledge of God, or of simply conceptualising all our inarticulate knowledge. On the contrary, ‘the transcendent intelligibility of God infinitely exceeds all that we can ever grasp or bring to articulate form’, so that our intuitive knowledge of God is never fully reducible to conceptual expression.Footnote ⁴⁰ Moreover, this intuitive first-level knowledge forms the basis of all further theological thought and remains the touchstone for every concept which we might develop. Einstein has said that ‘[t]he whole of science is nothing more than a refinement of every day thinking’Footnote ⁴¹ and in a similar way Torrance insists that our implicit inarticulate knowledge must govern all explicit conceptual knowledge. The ‘ground level of evangelical experience’ thus remains ‘the necessary basis, the sine qua non, of the other levels of doctrinal formulation developed from it’.Footnote ⁴² Indeed, at the higher levels of theological conceptualisation we are concerned only to investigate and to make explicit the ‘implicit pattern’ of God's threefold self-revelation as we have encountered it already in the gospel.Footnote ⁴³ Ultimately, then, ‘[i]t is only through relying implicitly on [the] inarticulate ingredient in knowledge, the content of which cannot be made fully explicit, that the most rigorous scientific operations are possible’.Footnote ⁴⁴ The second and third levels of Torrance's stratification model seek to give an account of such ‘rigorous scientific operations’.

At the second level, which Torrance calls the theological or scientific level, we seek to organise and to give theoretical expression to our intuitive first-level knowledge. This kind of theoretical organisation aims to uncover the inner connections in reality which have formed the basis of our experience of God through the gospel.Footnote ⁴⁵ This second level of thought therefore involves a movement beyond experience to the intelligible relations that are intrinsic to our experience without themselves being experienced.Footnote ⁴⁶ We thus ‘penetrate into the intelligible connections latent in reality that ground and control our basic experiences’, in order to achieve a theoretical understanding of such experiences.Footnote ⁴⁷ Although this level of theoretical thought requires the use of concepts and relations which may not seem to be connected to ordinary experience, these concepts and relations nevertheless arise from the experiential level and remain ‘epistemically correlated with it as refinements and extensions of the basic cognitions bound up with it’.Footnote ⁴⁸ This does not of course mean that our theoretical concepts are somehow determined directly by our intuitive knowledge of reality; rather, the concepts which we develop at this level are ‘creatively thought up under the constraint of reality’, and they function as ‘freely chosen fluid axioms’ which remain open to revision in light of further disclosures from reality.Footnote ⁴⁹

At this second level of theological knowledge, it is in particular the trinitarian relations in God's saving economy which constitute the object of our theorising. Through our experience of faith and worship, we become increasingly conscious of the threefold movement of God's revealing and reconciling love. We become conscious that underlying all our doxological and evangelical experience is the reality of God as Father, Son and Holy Spirit. In this way we are led to speak of the economic Trinity.Footnote ⁵⁰ The ‘inchoate form of the doctrine of the Holy Trinity’ which was latent in God's self-revelation is now given explicit formulation as ‘doctrinal knowledge of the Holy Trinity’.Footnote ⁵¹

According to Torrance, this movement from the evangelical level to the theological level is precisely the kind of movement that was involved in the deliberations of the Council of Nicaea. The Nicene fathers developed the all-important concept of the homoousion not through abstract theological speculation, but through an attempt to give expression to the reality which they had grasped intuitively at the level of evangelical and doxological experience. ‘Face to face with Jesus Christ their Lord and Saviour they knew that they had to do immediately with God, who had communicated himself to them in Jesus Christ so unreservedly that they knew him to be the very incarnation of God’.Footnote ⁵² In their personal union and communion with Jesus Christ, the Nicene fathers knew themselves to have entered into union and communion with the very being of God. They therefore needed to affirm the ‘bond in Being and Act between Jesus Christ and God’, and in order to express this bond they needed to formulate the entirely new concept of the homoousion.Footnote ⁵³ This concept clarifies the fact that in our personal encounter with Jesus Christ ‘we have to do directly with the ultimate Reality of God’Footnote ⁵⁴ it gives formal expression to the unity between our relation to Jesus Christ and our relation to God's own being. The homoousion thus expresses our most basic and most profound evangelical intuition about God: namely, that God is inherently in himself what he is towards us in Jesus Christ, and that the economy of God's grace in Jesus Christ is nothing other than a revelation of the trinitarian relations of God's own being.Footnote ⁵⁵

In this progression from the first to the second level, we have thus moved from an intuitive, experiential grasp of God's reality to a formalised theological account of the structures which underlie our evangelical experience. We have moved from a personal knowledge of Jesus Christ through the gospel to a conceptual understanding that in Jesus Christ we are in touch with ‘real, intelligible relations’ in God.Footnote ⁵⁶ We have therefore moved not away from the level of concrete experience but deeper into that level, by uncovering the patterns and structures which gave rise to our experience in the first place. This penetration into the structures of the divine reality continues at the third and highest of Torrance's levels.

At the highest level, best described as a meta-theological level, we are concerned to give a theoretical account of the deepest epistemological and ontological structure of our knowledge of God. At this level we have theology in its purest and most refined form; concepts formulated at this level constitute the ‘basic grammar’ of all theological thought, for it is only here that we have to do with ‘the ultimate relations intrinsic to God's own Being’, which as such must ‘govern and control all true knowledge of [God] from beginning to end’.Footnote ⁵⁷ The result, then, is an ‘ultimate theoretic structure’Footnote ⁵⁸ which can function in theology the way Einstein's relativity theory functioned in physics.Footnote ⁵⁹

By penetrating to this meta-theological level, we achieve both a deepening and a simplification of the theoretical organisation of second-level theological concepts. The theoretical formulations at this highest level are characterised by ‘logical economy and simplicity’ such formulations thus offer a ‘unitary basis for simplifying and unifying the whole body of our knowledge’ and for relativising or even discarding theological accretions.Footnote ⁶⁰ The stratification of knowledge, therefore, is somewhat like a pyramid: ‘from a broad basis, scientific inquiry advances through levels of increasing logical rigour and simplicity until it reaches the ultimate set of minimum intelligible relations in terms of which, as its ultimate grammar, the whole structure is to be construed’.Footnote ⁶¹

In theological thought, the movement from the second to the third level involves a conceptual transition ‘from the level of economic trinitarian relations. . . to the level in which we discern the trinitarian relations immanent in God himself’.Footnote ⁶² Thus, while the theological level concentrates on the economic Trinity, the meta-theological level is concerned with the ontological Trinity. As we probe more deeply into God's saving self-revelation, we are ‘compelled’ to acknowledge that what God is toward us in his trinitarian economy he is ‘antecedently and eternally in his own Being’.Footnote ⁶³ In this transition to the highest theological level, the homoousion remains decisive, since it signifies the unity between the economic trinitarian relations and the relations immanent in God's eternal being. Here too, then, God's self-revelation in Jesus Christ remains the focal point: there is no theological movement away from this self-revelation, but only a deeper grasp of its ultimate underlying structure.

As we concentrate on the homoousion of Jesus Christ, our thought is ‘lifted up from the level of the economic Trinity to the level of the ontological Trinity’, and it is here that we reach ‘the supreme point in the knowledge of God in his internal intelligible personal relations’.Footnote ⁶⁴ This level of theological conceptualisation requires the highly refined conception of perichoresis, which expresses the immanent coinherent relations of the Father, Son and Holy Spirit. According to the concept of perichoresis, these coinherent trinitarian relations must be predicated not only of the economy of God's threefold self-revelation, but also and primarily of God's own eternal being.

With this refined conceptualisation of the perichoretic intra-trinitarian relations, Christian theology has achieved what Torrance calls ‘the supreme point in our knowing of God’.Footnote ⁶⁵ For the perichoretic relations are ‘the ultimate constitutive relations in God’, and as such they also constitute ‘the ground upon which the intelligibility and objectivity of all our knowledge of God finally repose’.Footnote ⁶⁶ This means, then, that a refinement of our knowledge at this highest point of the theological pyramid opens the way for ‘a thorough refinement of all our theological beliefs and truths’.Footnote ⁶⁷

At this meta-theological level, as at the previous level, theological formulation is especially concerned with the development of new concepts and with the investment of existing terminology with new meaning. In the service of theological science we make use of ‘forms of thought and speech taken from our ordinary discourse but refined and redefined under the creative impact of divine revelation’.Footnote ⁶⁸ A constant danger in theological discourse, then, is that the pre-theological meaning of an appropriated term will exert an ‘inertial drag’ on the term's interpretation – as, for instance, the word ‘being’ illustrates with its tendency to lapse back into impersonal and untheological notions of ‘substance’.Footnote ⁶⁹ But, according to Torrance, this terminological danger simply highlights the inadequacy of all theological vocabulary, and such inadequacy is itself an important aspect of the proper function of theological terms. ‘[T]he fragility of our theological terms and the inadequacy of our use of them. . ., paradoxically, play a significant role in the truth and precision of their semantic reference to the Truth of God beyond themselves’.Footnote ⁷⁰ After all, our concepts do not possess truth in themselves, but they are true only to the extent that they refer beyond themselves to the reality of God. And it is precisely by functioning in this way that theological terms like homoousion and perichoresis prove so vital and so indispensable. Referring beyond themselves, such formulations point us to the trinitarian structure of God's saving economy and, finally, of his own inner being.

Implications of Torrance's model

Although Torrance's stratification model may provide insights into the historical development of some specific Christian doctrines, it is important to note that this model is not intended to offer a general analysis of the way all doctrines develop. Torrance is concerned not with the formal structure of theological positions in general, but with the structure of all theological thought as a whole. He is concerned to uncover the very ‘ground and grammar’ of the entire theological enterprise. It is for this reason that Torrance concentrates so sharply on the doctrine of the Trinity, for in his view the trinitarian relations constitute the single highest level of all theological truth. The stratification model is thus an elaborate attempt to demonstrate the prime importance of a knowledge of the trinitarian relations, and to indicate the way in which the concept of the trinitarian relations functions as the fundamental organising principle of all theology.

Torrance's model should not, moreover, be understood as a reductionist attempt to restrict all theological knowledge merely to three neat levels. Although, like Einstein, Torrance presents the stratification of truth in the form of three main levels, he affirms nevertheless that the number of levels is theoretically indefinite.Footnote ⁷¹ Indeed, underlying Torrance's whole account of stratification is a commitment to the transcendence of divine reality – we can never master God's reality, for it always utterly ‘transcends conceptual control’.Footnote ⁷² Torrance argues, in fact, that all theological knowledge is relativised by the ineffable objectivity of God's reality. Reality manifests ‘such an infinite depth of incomprehensibility’ that our theoretical concepts and statements remain at best provisional.Footnote ⁷³ This is true even in the natural sciences, and it is all the more true in theological science, since the divine object of theology is ‘infinitely inexhaustible in the Truth and Intelligibility of his own eternal Being’.Footnote ⁷⁴ The being of God is thus ‘open to ever deepening understanding on our part’, while the concepts and statements with which we articulate our knowledge of God are ‘ever open to further clarification, fuller amplification, and change’.Footnote ⁷⁵

There is therefore in Torrance's thought an ‘inner ratio’ between ontological objectivity and epistemological relativity.Footnote ⁷⁶ Far from seeking to confine the knowledge of God within the boundaries of a stratified epistemological structure, Torrance highlights the sheer transcendence of God's reality and the subsequent relativity and revisibility of all true knowledge of God.

Further, Torrance's model of the stratification of knowledge offers a way to move beyond dualist thought-forms towards a unitary vision of theological truth. A recognition of the stratification of theological knowledge allows us to concentrate all such knowledge on ‘the objective centre and content of God's self-revelation in Jesus Christ’.Footnote ⁷⁷ This concentration in turn enables us ‘to organise our knowledge into various levels of thought with fewer and fewer fundamental concepts’.Footnote ⁷⁸ A recognition of theological stratification entails, in other words, the acknowledgement that some theological concepts are basic or central while others are derivative or peripheral. The whole diverse body of theological knowledge can thus be unified through an awareness of the stratification of that knowledge.

For Torrance, such an awareness is especially needed in our contemporary theological situation, characterised as it is by a bewildering multiplicity of beliefs.Footnote ⁷⁹ In this situation, Torrance notes, it can be difficult to distinguish ‘between what is basic and essential and what is peripheral and even perhaps. . . irrelevant’.Footnote ⁸⁰ What is needed then is a rigorous analysis of the whole corpus of theological knowledge, in which we ‘isolate the core of basic and central theological concepts. . ., distinguishing them from derived notions of an intermediary and secondary nature’.Footnote ⁸¹ This in turn enables us to grasp the ‘inner coherence and unity’ of all theological knowledge, so that we can proceed to ‘comb through the whole corpus of accumulated beliefs and doctrines in the service of clarification and simplification’.Footnote ⁸² A recognition of the stratified structure of our knowledge of God can therefore provide us with a kind of Ockham's razor with which we can ‘slice away all unnecessary accretions and layers in the elaborated machinery of our thought’.Footnote ⁸³ In all this, Torrance's basic realist axiom is decisive: knowledge is governed by its object. The ontological unity of divine reality opens the way for the unification and simplification of our knowledge of that reality.

This unitary vision of theological thought has important ecumenical implications. An awareness of the stratification of truth, Torrance suggests, can enable theological thinkers from different traditions to transcend divisive dualist modes of thought and to move towards a shared vision of the basic grammar of all theological knowledge. As members of diverse traditions penetrate ever more deeply into the highest level of theological truth, i.e. the level of intra-trinitarian relations, they are thus able to achieve ‘profound advance and agreement’.Footnote ⁸⁴

Finally, perhaps the most valuable aspect of Torrance's model is its emphasis on the continuing correlation between the different levels of theological knowledge. Torrance insists that we must move from the basic level of evangelical experience to the higher levels of scientific conceptualisation without allowing these levels to become detached from one another. On the one hand, our experiential knowledge of Jesus Christ lapses into mere subjectivism if it is detached from its underlying ontological structures; and, on the other hand, our refined theological concepts become meaningless abstractions if they are severed from the empirical reality of our creaturely world. The distinctive levels of truth must therefore remain in ‘cross-level coordination with one another’,Footnote ⁸⁵ so that our empirical experience remains correlated with the trinitarian relations and our theoretical understanding of these relations remains grounded in empirical experience.Footnote ⁸⁶ The coordination of the conceptual with the experiential should not be taken to mean that every concept must have some specific empirical correlate; it means, rather, that our theological concepts must be ‘integrated within a coherent system’ which as a whole is correlated with the empirical world in which the event of God's self-revelation takes place.Footnote ⁸⁷ Even the highly refined and seemingly abstract concept of perichoresis remains empirically correlated with the concrete ground from which it took its rise – the ground of ‘the incarnational activity of God within the spatio-temporal structures of our world’.Footnote ⁸⁸

The movement from experiential and intuitive knowledge of Jesus Christ to higher levels of theological reflection is therefore not a movement away from Jesus Christ into realms of abstract speculation, but it is one in which we penetrate ever more deeply into that same divine reality which we have already apprehended experientially. The personal reality of Jesus Christ thus remains firmly at the centre of this whole complex process of theological thought. It is in fact for just this reason that each successive level of theological knowledge becomes conceptually simpler and narrower: each level hones in more sharply on the act of God in Jesus Christ, until we have arrived at a minimum set of concepts and relations which expresses the deepest reality of who Jesus Christ is. The movement from the economic to the ontological Trinity, for instance, is nothing other than a movement of increasingly sharp concentration on the structure of God's self-revelation in Jesus Christ. In Torrance's words: ‘As the different levels coordinated in this stratified way become narrower and narrower, they focus our thought more and more sharply upon the fundamental truths of the Gospel of divine salvation through Jesus Christ and in the Spirit with which we are concerned in the ground level.’Footnote ⁸⁹