What Liam de los Reyes accomplishes in The Earth is the Lord’s is a marvelous example of a detailed, historically informed, and meticulously presented argument at the intersection of economics, natural law, and Catholic social teaching. It is a study that traces the genealogy of the perspective that regards the purpose of property – of saying that ‘this is mine’ to the exclusion of others’ claim on it – as ultimately one designed to more easily achieve one of the goals behind God’s creative act: to provide for the flourishing of all people.

The genealogy of this perspective unfolds throughout the book’s five chapters, opening with the intrusively intriguing question: if God would seem to be the person who has a claim on everything that exists, then on what grounds can one say that we, human beings, own anything at all? In chapters 1 and 2, Reyes draws our attention to the medieval period. Here Reyes notes how scholastics like Gratian – and later, thinkers such as Rufinus, Hugguccio, and Aquinas – constructed their theologies of property based on a common set of convictions that each of them would harmonise differently: that 1) dominion, the power to direct and order the use –of all things, ultimately belongs to God; that 2) the earth is for the sustenance of each and all alike; and that 3) property becomes yours and mine, in fact, to alleviate the needs of others (i.e., property is a ‘power of distribution,’ pp. 15ff.).

Unsurprisingly, Aquinas’ particular synthesis emerges as authoritative in the centuries that succeeded him. His persepctive maintains that property, and the various property ‘regimes’ that distribute it, exist as so many ways to realise responsibly the principle of stewardship – the principle that ‘resources are best managed and society best served when someone has responsibility for them and everyone knows who has responsibility for what’ (p. 84). But never to be forgotten is that one is not a steward in order to hoard what one has; rather, one holds property in recognition of the more primary moral imperative of ‘common dominion,’ meaning that property is held ‘as though it were common and available for use by others in order to satisfy their needs’ (p. 91), in fulfillment of the divine intention of creating.

The remainder of the book draws the reader into the contemporary period, beginning with a schematic presentation of the principles regarding property inherited by the modern period from the pens of the scholastics (chapter 3). One important takeaway from this chapter is Reyes’ successful articulation of the norms surrounding legitimate property regimes, namely that any moral distribution of property in society must be equitable (i.e., allow for each person to receive what is due to them) in view of human beings’ fundamental moral equality, and that any given property regime must allow for a person to achieve a ‘good or decent life’ (p. 120), for which the ability to possess and dispose of goods is necessary.

It is in Reyes’s fourth chapter, engaging the philosophy of John Locke, where we see how this medieval imagination was transformed in the modern period. Here, Reyes performs an extremely close and thoughtful reading of Locke’s philosophical innovation, his labour-mixing theory of property, in which Locke maintained that something in nature becomes one’s property if one has ‘mixed his labor with, and joined to it something that is his own’ (p. 140) – a principle that Locke not only applied to things but also to land itself, enabling one to generate property in ‘as much land as a man tills, plants, improves, cultivates, and can use the product of’ (p. 141). Particularly thrilling in this chapter is Reyes’ argument connecting Locke’s theory to theories used by colonists to dispossess indigenous populations of their property. But most compelling is Reyes’ comparative assessment of how the modern imaginary concerning property inverted the scholastic one: whereas in the scholastic period, property served certain political goals surrounding the shape of human flourishing, in the modern period, political societies existed to protect the private property of a given society’s inhabitants.

With this divergence, Reyes approaches the present day, which he accesses through the lens of Catholic social teaching on property. This chapter features an examination of papal writings from Leo XIII through Francis, resulting in an authoritative grounding of various Catholic convictions concerning property that those familiar with Catholic social teaching will recognise well (e.g., the conviction that ‘private property has a social mortgage’). The picture that emerges with crystal clarity by the time Reyes completes his argument is that Catholic social teaching’s convictions regarding property ultimately represent a contemporary elaboration of the scholastic inheritance Reyes has profiled in the book’s preceding chapters. From this, a number of felicitous consequences follow, all of which make this book a commendable read, especially for ethicists and for scholars of the natural law. One of them directs us immediately to the timely question of how to think about the distribution of wealth today, especially in wealthy western societies, and about the political actions we might undertake to bring about a more just society.