The Moon and Sixpence by William Somerset Maugham

During the journey back to England I thought much of Strickland. I tried to set in order what I had to tell his wife. It was unsatisfactory, and I could not imagine that she would be content with me; I was not content with myself. Strickland perplexed me. I could not understand his motives. When I had asked him what first gave him the idea of being a painter, he was unable or unwilling to tell me. I could make nothing of it. I tried to persuade myself than an obscure feeling of revolt had been gradually coming to a head in his slow mind, but to challenge this was the undoubted fact that he had never shown any impatience with the monotony of his life. If, seized by an intolerable boredom, he had determined to be a painter merely to break with irksome ties, it would have been comprehensible, and commonplace; but commonplace is precisely what I felt he was not.

At last, because I was romantic, I devised an explanation which I acknowledged to be farfetched, but which was the only one that in any way satisfied me. It was this: I asked myself whether there was not in his soul some deep-rooted instinct of creation, which the circumstances of his life had obscured, but which grew relentlessly, as a cancer may grow in the living tissues, till at last it took possession of his whole being and forced him irresistibly to action. The cuckoo lays its egg in the strange bird's nest, and when the young one is hatched it shoulders its foster-brothers out and breaks at last the nest that has sheltered it.