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and peculiar to them; whence it follows that there must be as many independent characters as there are single objects, in the sense in which a thing and a simple part of it are distinct things. But of corpuscles alone there are doubtless more than 10⁶⁴ in the visible universe, and therefore much more than that number of mutually exclusive, logically simple hypotheses might be proposed to explain any given fact, while the number that would ever occur to the human mind cannot exceed 10⁴. Thus the odds against any given hypothesis being reached without a natural aptitude would be say 10⁶⁰ to 1.