This volume is the third of Pierre Rousselot's Philosophical Works. It includes seven essays written between 1908 and 1914, one year before his death (two were published posthumously: "A Theory of Concepts by Functional Unity" and "Idealism and Thomism"). These essays offer a complement to Rousselot's views on epistemology, which he presented in Intelligence and constitute the core of his Neo-thomistic philosophy. However, besides making his views more clear and specific, these essays also go further than what we had in Intelligence. It is an effort to offer a systematic view on knowledge as the fusion of the knower and the known. These views go significantly beyond St Thomas' doctrine and some of them are rather daring, like Rousselot's notion of an Angel-humanity. The common thread of these essays is the role of love in knowledge. Rousselot's expands St. Thomas' view on knowledge on the mode of nature (per modum naturae) or connaturality and understands love both as an attitude of the knower, who must be in a certain disposition toward the object, and a characterization of the relationship between knower and known. From the introduction by Pol Vandevelde.