As distinct from accidental findings, great discoveries are creative acts, the nature of which is incompletely understood. In his recently published work, The Body in Question,1 Jonathan Miller looks for sources of discovery in the realm of metaphor: "Since finding out what something is is a matter of discovering what something is like, the more impressive contribution to growth of intelligibility has been made by the application of suggestive metaphors."
Pursuing this thought further, Miller evolves the thesis that great discoveries in the field of human physiology owe much to technological inventions for "suggestive metaphors." A prime example, he points out, is the fire-pump. Introduced to the streets of London in the 17th century, this pump provided William Harvey with a technological image of propulsion for his discovery of the circulation, as the sight of venous valves evoked the image of valves in the pump.
Another image, that of