The writer's only responsibility is to his art. He will be completely ruthless if he is a good one... If a writer has to rob his mother, he will not hesitate; the "Ode on a Grecian Urn" is worth any number of old ladies.
Ideas are like fish. If you want to catch little fish, you can stay in the shallow water. But if you want to catch the big fish, you've got to go deeper.