What books on love by our people?

What books do you know of written by our people on the subject of love, especially, the love of God? (I’m not looking for books on marriage and family.)

I have one in Portuguese, that examines 1 Cor 13. I can’t recall any others, offhand.

Article suggestions are fine, I suppose, but they ought to be longish and more in-depth, rather than devotional. Still, a book would be gold.

#brotherhood, #love