The tears filled his mild eyes; something precious had passed away. This was the pang that had been sharpest during the last few years – the sense of ebbing time, of shrinking opportunity; and now he felt not so much that his last chance was going as that it was gone indeed. He had done all that he should ever do, and yet he had not done what he wanted.
-Henry James, “The Middle Years”
Literature and the Tortoise 