The Order of Things is an exploration of the metaphysical principle, "Every agent acts for an end".

In the first part, Fr. Garrigou-Lagrange sets forth the basics of the Aristotelian metaphysics of teleology, defending its place as a central point of metaphysics. After defending its per se nota character, he summarizes a number of main corollaries to the principle, primarily within the perspective established by traditional Thomistic accounts of metaphysics, doing so in a way that is pedagogically sensitive yet speculatively profound.

In the second half of The Order of Things, Garrigou-Lagrange gathers together a number of articles which he had written, each having some connection with themes concerning teleology. Thematically, the texts consider the finality and teleology of the human intellect and will, along with the way that the principle of finality sheds light on certain problems associated with the distinction between faith and reason. Finally, the text ends with an important essay on the principle of the mutual interdependence of causes, causae ad invicem sunt causae, sed in diverso genere.