There is no fourth, as will be proved. This list of categories may be distinguished from other lists as the Ceno-Pythagorean Categories, on account of their connection with numbers. They agree substantially with Hegel’s three moments. Could they be attributed to any thinker in well-known history, that would be almost enough to refute their claims to primitivity. It has occurred to me that perhaps Pythagoras brought them from Media or Aria; but careful examination has convinced me that there was not among the Pythagoreans the smallest approach to anything resembling the categories.
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