The primary distinction of the artist is that he must actively cultivate that state which most men, necessarily, must avoid: the state of being alone.
Per The Paris Review's "The Art of Fiction No. 151, Martin Amis said,
"The first thing that distinguishes a writer is that he is most alive when he is alone."
And we related previously that Jenn Granneman shared on the blog Introvert, Dear that John Green, The Fault in Our Stars author, opined:
“Writing is something you do alone. It’s a profession for introverts who want to tell you a story but don’t want to make eye contact while doing it.”
Of course, there are a number of writers who are not introverts (e.g., Hemingway); thus, like Baldwin advised, they must actively cultivate the state of being alone to attain the state of feeling alive.