Humboldt's Gift is a Pulitzer Prize-winning novel by Saul Bellow, published in 1975 and based on experiences in Bellow's own life.

The main symbol in the book is writing -- not the writing of the book itself, but the writing that takes place inside the book. Charlie, the protagonist, and Humboldt, his tortured friend, both write works of great meaning, but while Charlie is generally happy in his life, Humboldt is under constant mental stress from manic depression, drugs, and alcohol. The two meet because of Humboldt's book on poetry, and then their work both deepens and damages their friendship; Charlie becomes suddenly successful and Humboldt, in the grip of depression, rejects him as a sellout.

Humboldt held the money against me... "He arrived from Madison, Wisconsin, and knocked on my door. Now he's got a million bucks. What kind of writer or intellectual makes that king of dough... who the hell is [he] to become so rich?"
(Bellow, Humboldt's Gift, Google Books)

Their respective writing is what gets in the way; Humboldt is jealous but can't admit it, so he attacks Charlie's integrity as an artist. Later, the titular gift turns out to be an unpublished work from Humboldt, given to Charlie as a gesture of apology, and also allowing him to keep control of his intellectual ideas, which have been plagiarised by a film company. Thus, Humboldt shows how writing is a thing of love, of hate, and also of protection.