These two rational faculties may be designated the Scientific Faculty and the Calculative Faculty respectively; since calculation is the same as deliberation, and deliberation is never exercised about things that are invariable, so that the Calculative Faculty is a separate part of the rational half of the soul.

The soul has two parts, one rational and the other irrational. Let us now similarly divide the rational part, and let it be assumed that there are two rational faculties, one whereby we contemplate those things whose first principles are invariable, and one whereby we contemplate those things which admit of variation.

Friendship is two souls inhabiting one body.

Two characteristic marks have above all others been recognized as distinguishing that which has soul in it from that which has not - movement and sensation.

Revolutions are effected in two ways, by force and by fraud.