Offers a systematic treatment of St. Thomas Aquinas's account of the metaphysical relations of unity-to-union and unity-to-participation in God as the key structuring elements to the nature of love and friendship.

"Flood treats big themes in a small space - with particular clarity to boot. This is no small achievement, and it speaks to the maturity of his understanding. Thinking of love and self-love in terms of their ontological foundations richly illuminates them. Being both rich and clear, this book is likely to prompt an abundance of further reflection in its readers."-The Review of Metaphysics