if men were like atoms we could not detect them

An example of an analogy used to exlpain a scientific idea:

"…it is due to the fact that an unelectrified [neutral] atom is so elusive that unless more than a million million are present we have no means sufficiently sensitive to detect them, or, to put it in another way, unless we had a better test for a man than we have for an unelectrified molecule, we should be unable to find out that the earth was inhabited."

J. J. Thomson

J. J. Thomson (1914) 'The Atomic Theory'

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