Nietzsche repeatedly portrays himself as an advocate of what he calls a ‘philosophy of becoming’. While in his early Untimely Meditations he had considered the ‘doctrine of sovereign becoming’ to be ‘true but deadly’, from the middle-period Human, All Too Human up to and including his last writings he urges us to embrace this doctrine wholeheartedly. He consistently links the view of the world as being in a state of constant flux with the teachings of Heraclitus, the one philosopher whom he praises to the very end of his sane life. Exactly what such a doctrine amounts to is a question that has not hitherto been subjected to the substantial treatment that it deserves, and it is this issue that Robin Small sets out to address.

Time and Becoming in Nietzsche's Thought falls into two main parts. Chapters 1–3 deal with various doctrines and ideas that can be attributed to Nietzsche on the topics of time and becoming, while Chapters 4–8 consist for the most part of a detailed analysis of one section from Part III of Thus Spoke Zarathustra, entitled ‘On the Vision and the Riddle’. In the earlier chapters, Small presents what he calls the ‘doctrine of absolute becoming’ itself and considers the ‘conflict model of becoming’ Nietzsche advances to fill in the details of his picture. This is supplemented by an analysis of Nietzsche's so-called ‘Time-Atom Fragment’, which Small sees as offering ‘nothing less than a Heraclitean science of nature’ (57), that is, as spelling out the details of the Heraclitean conception of nature on which the model of becoming rests.

For Nietzsche, the realisation that everything is in a state of becoming is closely tied to his rejection of the Platonic metaphysical tradition (of which he sees the continuation in Kant's thing-in-itself), in which a world of stable, unchanging objects is held to underlie the fleeting world of appearances. This Platonic tradition can itself, on his view, be traced back to a wrong turning taken early on in the history of philosophy by Parmenides, who looked for a changeless grounding element for the changing world of appearances, in opposition to Heraclitus' embrace of flux. Nietzsche wants to return to the Heraclitean position in urging that we should not look beyond the flux itself for the reality of the world. He thus in some sense wants to turn the clock back and resume philosophy where Heraclitus left off; the ancient Greeks, he suggests in The Antichrist, had the materials for a coherent philosophy of nature at their disposal but were thrown off-course by the Parmenidean turn. A clear sense of Nietzsche's aspiration to realise the potential of the Heraclitean conception of nature, and undo the mistakes of Parmenides, emerges from Small's detailed and persuasive analysis of Nietzsche's account of this problematic in pre-Socratic philosophy in the opening sections of the book.

Nietzsche, as Small rightly emphasises, intends the view that everything is fundamentally or ‘really’ flux in a more radical sense than just that the unchanging can be explained in terms of the changing; his view seems to be literally that everything is always undergoing change. As he sometimes says, ‘there are no things’ at all. How does Nietzsche justify this view? It is surely not enough to say that ‘the fact of becoming […] cannot be denied without evident absurdity’ (20). While Small suggests that Nietzsche regards this ‘fact’ as evident to ‘immediate experience’, such an assertion stands in tension with the claim that ‘the human mind is incapable of grasping becoming’ (3) – that our perceptual apparatus predisposes us (as Nietzsche repeatedly argues) to see the world as more stable, less fluid than it actually is. What self-evidence the fact of becoming does have would thus seem to rest exclusively, on Small's account, on mental introspection (a cogito-like exercise supposedly showing that ‘rational thinking is in motion’; (20), quoting Nietzsche's Philosophy in the Tragic Age of the Greeks), but this seems to be insufficient to show that the world itself is in flux. The only real indication we get of an argument for Nietzsche's Heraclitean conception is in Chapter 3, devoted to the ‘Time-Atom Fragment’, an intriguing unpublished text from 1873. This Small sees as spelling out Nietzsche's ‘Heraclitean science of nature’ (if only in sketch form). But it is questionable whether this fragment can effectively fulfil the role of supporting Nietzsche's claims elsewhere about the Heraclitean flux. In the ‘Time-Atom Fragment’ Nietzsche speculates that Boscovich's theory of extensionless, discrete space-atoms can be supplanted by a theory of discrete time-atoms out of which space is itself constructed. It is central to Nietzsche's conception of time here that it is not continuous, but consists of discrete points which act on each other ‘at a distance’. Since, as Small admits, this contradicts Nietzsche's view of time almost everywhere else, it is doubtful how useful the ‘time-atom fragment’ can be for the purpose he intends.

Further problems emerge with the ‘conflict model of becoming’ that Small identifies in Nietzsche. Firstly, the flux is to be thought of as driven onwards by a process of conflict between opposites (a feature of Heraclitus' account that appealed to Nietzsche's sense for the agonistic). However, it is not clear what such conflict can be between, given that Nietzsche denies that there are any entities or qualities that can stand in a fixed, permanent opposition to each other (because of his radical interpretation of the doctrine of becoming: there is nothing self-identical). A crucial discussion of the philosophy of becoming in the opening aphorisms of Human, All Too Human (a text Small surprisingly ignores) closely ties it with the denial of the existence of opposite properties or values at all (reiterated in later texts such as Beyond Good and Evil). Furthermore, it seems to be suggested by Small that Nietzsche's insistence that ‘every occurrence is a conflict’ is linked with his denial of causation, a foray into natural-scientific issues where Nietzsche seems to be on shaky ground. Small unfortunately never gives these questions the sustained attention they deserve, as he is diverted from his discussion of the ‘conflict model’ by a consideration of ‘conflict within the individual person’ (40), which does not throw light on the central claim that a conception of nature featuring causality and stable objects should be replaced with one of conflictual flux.

Chapters 1–3 in general reflect the problematic nature of Nietzsche's discussions (usually in short Nachlaß fragments) of issues in natural science. Nietzsche's remarks are often of a provisional, speculative nature and are scattered across notebooks from different periods. Furthermore, Nietzsche never immersed himself deeply in the study of the sciences, even if Small is right in pointing to his interest in the work of authors such as Boscovich and Zöllner (figures he seems to have appreciated, in the first instance, for their iconoclastic status more than anything). While early in his intellectual career he once resolved to study chemistry, and he showed a lasting interest in natural-scientific topics, he never really entered scientific debates fully. This state of affairs leaves the impression that Nietzsche's apparent doctrines on these topics can hardly be unified into a satisfying and coherent whole without large-scale reconstruction. As a result, although Small's analyses in the first half of his book are instructive taken by themselves, it is difficult to distil an overall conception of what becoming is supposed to be, and why, according to Small, for Nietzsche becoming is a fact, and his ‘models’ of time a set of interpretations of that fact (2).

These interpretations are set out in the second half of the book, dealing with Zarathustra. Here we are offered a series of ‘modes of temporality’ which correspond to Zarathustra's various ‘ways’ (such as walking, running, and climbing) and embody different ‘forms of life’. While Small's interpretation of Zarathustra is often searching and suggestive, it is not always clear how its metaphorical world bears on Nietzsche's conception of time and becoming. At times it seems as if Small's interpretation of the doctrine of the eternal recurrence as a doctrine about time can have the role of identifying Nietzsche as taking up a particular position in the philosophy of time since McTaggart, as when he writes, ‘McTaggart's A-series of past, present and future is Nietzsche's standard way of stating the doctrine of eternal recurrence’ (140). Nietzsche's use of tensed language is not, however, sufficient to demonstrate that he holds that tensed language is irreducible to untensed time-language, as an A-theorist of time would have to claim. Small offers a detailed reading of an episode from ‘On the Vision and the Riddle’ where Zarathustra poses a riddle to the ‘spirit of gravity’ in the form of a dwarf. He asks the dwarf to consider the lanes that lead out from a gateway entitled ‘Moment’, one leading eternally back, the other eternally onward, and asks whether these ever meet. The dwarf replies that ‘time is a circle’. While Small demonstrates persuasively that the lanes are meant to symbolise the course of past and future time, it is not clear how far this gets us in attributing any particular view of time to Nietzsche. This situation is not helped by the way Nietzsche leaves it unclear whether the dwarf's reply is to be endorsed. All this makes it difficult not to feel that Zarathustra is an even more problematic place to look for Nietzsche's views on time than his unpublished fragments.

The metaphorical language of Zarathustra, further, presents notorious problems. Small defends his use of this text on the basis that Nietzsche's ‘insistence on the metaphorical character of our ordinary concepts […] undermines the whole distinction between the metaphorical and literal’ (ix–x). If this really were Nietzsche's view, it is not immediately clear what the consequences would be, in particular for attempts to make literal statements (which is presumably what Small's book should be primarily read as consisting of). But a problem in any case remains where evidently metaphorical statements seem to defy literal interpretation. Sometimes Small himself uses metaphorical language, as when he says that ‘[i]n the hour, past and future are able to dwell together’ or that the ‘Nietzschean god […] dances with an expressiveness that says all that in the end needs to be said about becoming’ (16). This points to the difficulties facing any interpreter of a text such as Zarathustra: it cannot really be done justice either by attempting to distil its insights into theoretical philosophical claims or by responding to it in a metaphorical vein that leaves commentary and text equally mysterious. When these problems are combined with those of Nietzsche's texts dealing with natural science, it becomes clear how great the challenges are facing Small's presentation of his ‘philosophy of becoming’. While Small seems to suggest that such a philosophy can be coherently presented, Nietzsche's attempts to deliver on his claims to be able to provide one appear to be more provisional and fragmentary than he allows. Small's analyses contain many insights that will interest Nietzsche scholars (such as the parallel he draws between ‘The Vision and the Riddle’ and a story by Mark Twain that Nietzsche knew), drawing on his intimate knowledge of Nietzsche's own reading. However, it is difficult to avoid the impression that, however searching its analyses of the texts it treats may be, a satisfyingly coherent and unified philosophy of becoming does not ultimately materialise.