tial sense. For example, if
I were to attempt to classify the arts, which I shall not do, I should have
to recognize, as one of them, the art of illumination, and should have
occasion to remark that lamps form a true, real, and natural class, because
every lamp has been made and has come into being as a result of an aim
common and peculiar to all lamps. A class, of course, is the total of
whatever objects there may be in the universe which are of a certain
description. ..." - CSP, CP1:204
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