Amazon offers The Four Loves Kindle Edition for  

Product Description: 
The revered author's classic work that examines the four types of human love: affection, friendship, erotic love, and the love of God.In this work Lewis examines four varieties of love, as approached from the Greek language: storge, the most basic form; philia, the rarest and perhaps most insightful; eros, passionate love; and agape, the love of God, the greatest and least selfish. Throughout this compassionate and reasoned study, he encourages readers to open themselves to all forms of love—the key to understanding that brings us closer to God. "There is no safe investment. To love at all is to be vulnerable . . . draw nearer to God, not be trying to avoid the sufferings inherent in all loves, but by accepting them and offering them to Him; throwing away all defensive armor. If our hearts need to be broken, and if He chooses this as the way in which they should break, so be it."