I have long believed that an experimentalist should not be unduely inhibited by theoretical untidyness. If he insists in having every last theoretical T crossed before he starts his research the chances are that he will never do a significant experiment. And the more significant and fundamental the experiment the more theoretical uncertainty may be tolerated. By contrast, the more important and difficult the experiment the more that experimental care is warranted. There is no point in attempting a half-hearted experiment with an inadequate apparatus.

As quoted by W. Happer, P. J. E. Peebles, and D. T. Wilkinson. Biographical Memoirs, Robert Henry Dicke May 6, 1916 — March 4, 1997.