Many a man floated in water before Archimedes; apples fell from trees as long ago as the Garden of Eden, and the onrush of steam against resistance could have been noted at any time since the discovery of fire and its use under a covered pot of water. In all these cases it was eons before the significance of these events was perceived. Obviously a chance discovery involves both the phenomenon to be observed and the appropriate, intelligent observer.

— Walter Cannon, The Way of an Investigator, 1945