509.
The kingdom of desires out of which logic grew: the gregarious instinct in the background. The assumption of similar facts is the first condition for "similar souls." For the purpose of mutual understanding and government.
510.
Concerning the origin of logic. The fundamental proneness to equalise things and to see them equal, gets to be modified, and kept within bounds, by the consideration of what is useful or harmful—in fact, by considerations of success: it then becomes adapted in suchwise as to be gratified in a milder way, without at the same time denying life or endangering it. This whole process corresponds entirely with that external and mechanical process (which is its symbol) by which the protoplasm continually assimilates, makes equal to itself, what it appropriates, and arranges it according to its own forms and requirements.
511.
Likeness and Similarity.
1. The coarser the organ the more apparent likenesses it sees;
2. The mind will have likeness—that is to say, the identification of one sensual impression with others already experienced: just as the body assimilates inorganic matter.
For the understanding of Logic:—