When one thinks of C.S. Lewis's nonfiction, generally the works that come to mind are the apologetics such as Mere Christianity. While there's nothing wrong with that, it's unfortunate that some of his lesser known offerings aren't more fully explored.

Take 'The Four Loves', a beautiful examination of the four 'types' of love we experience- Storge (affection), Eros (sexual passion), Philios (friendship), and Agape (God's love; selfless love). In the hundred and fifty or so pages Lewis leads us through love's trials and tribulations, in the tender, wise prose that is the hallmark of all of his best work. Arguing that we shouldn't avoid love- that in fact, it is the absence of love that makes a Hell, more than any flames or sulfur- he examines how we should best embrace it, and invites readers to examine what place each of the loves plays in his or her own life.

A classic- one many more should read.