Every revolutionary idea — in science, politics, art, or whatever — seems to evoke three stages of reaction. They may be summed up by the phrases:
(1) "It's completely impossible — don't waste my time";
(2) "It's possible, but it's not worth doing";
(3) "I said it was a good idea all along."

The Promise of Space (1968); This and similar statements attributed to Mahatma Gandhi and J. B. S. Haldane may ultimately be derived from a statement attibuted to Arthur Schopenhauer: - On Clarke's Laws