If you don’t get the newsletter, Brain Pickings, every Sunday, you really are missing a compendium of fascinating people and thoughts. This week is especially great. Of all the wonderful books from Steinbeck, from Grapes of Wrath , East of Eden, Of Mice and Men, the editors found a letter defining love that he wrote in 1958.

Here is a brief excerpt — after all Sundays and love do kind of go together. The quote shows what a wise man he is. Wisdom, not just knowledge, is what makes a writer great. Here’s Steinbeck’s proof:

There are several kinds of love. One is a selfish, mean, grasping, egotistical thing which uses love for self-importance. This is the ugly and crippling kind. The other is an outpouring of everything good in you — of kindness and consideration and respect — not only the social respect of manners but the greater respect which is recognition of another person as unique and valuable. The first kind can make you sick and small and weak but the second can release in you strength, and courage and goodness and even wisdom you didn’t know you had.

He sure knew his stuff, didn’t he? Understanding such distinctions make the difference between happiness and hurt over a lifetime because often it takes what feels like forever to realize there’s this difference that’s genuine, huge and life-altering.