Henry James appears to have used the multiple personality “We” and “Our” in his famous quotation on “The Madness of Art,” when you read what follows it.

Quoting from his short story, “The Middle Years”:

"You're a great success!" said Doctor Hugh, putting into his young voice the ring of a marriage-bell.

Dencombe lay taking this in; then he gathered strength to speak once more. "A second chance—THAT’S the delusion. There never was to be but one. We work in the dark—we do what we can—we give what we have. Our doubt is our passion and our passion is our task. The rest is the madness of art."

"If you've doubted, if you've despaired, you've always 'done' it," his visitor subtly argued.

"We've done something or other," Dencombe conceded.

If you consider the “we” and “our” in the famous passage only, you might think that the novelist is referring to writers in general, but “We’ve done something or other” shows that he is referring to himself only, and that he experiences himself as plural.