Probably the weakness of his own theory did not escape him, for he never subsequently recurs to it.[259] Aristotle’s work on reproduction is supposed by many to contain a reference to his distinction between the two Reasons, but we are convinced that this is a mistake. What we are told is that at the very first formation of a new being, the vegetative soul, being an exclusively corporeal function, is precontained in the elements furnished by the female; that the sensitive soul is contributed by the male (being, apparently, engendered in the semen by the vital heat of the parent organism); and, finally, that the rational soul, although entirely immaterial, is also carried in with the semen, into which it has first been introduced from without, but where, or when, or how is not more particularly specified.[260] But even were the genetic theory in question perfectly cleared up, it would still throw no light on the distinction between active and passive reason, as the latter alone can be understood by the rational soul to which it refers. For we are expressly informed—what indeed hardly required to be stated—that the embryonic souls exist not in act but in potency.[261] It seems, therefore, that Mr. Edwin Wallace is doubly mistaken when he quotes a sentence from this passage in justification of his statement, that ‘Aristotle would seem almost to identify’ the creative reason ‘with God as the eternal and omnipresent thinker;’[262] first, because it does not refer to the creative Nous at all; and, secondly, because, if it did, the words would not stand the meaning which he puts upon them.[263]