Thus much for their logic. The ethical branch of philosophy they divide as follows : (1) the topic of impulse ; (2) the topic of things good and evil ; (3) that of the passions ; (4) that of virtue ; (5) that of the end : (6) that of primary value and of actions ; (7) that of duties or the befitting ; and (8) of inducements to act or refrain from acting. The foregoing is the subdivision adopted by Chrysippus, Archedemus, Zeno of Tarsus, Apollodorus, Diogenes, Antipater, and Posidonius, and their disciples. Zeno of Citium and Cleanthes treated the subject somewhat less elaborately, as might be expected in an older generation. They, however, did subdivide Logic and Physics as well as Ethics. An animal's first impulse, say the Stoics, is to selfpreservation, because nature from the outset endears it to itself, as Chrysippus affirms in the first book of his work On Ends : his words are, " The dearest thing to every animal is its own constitution and its consciousness thereof " ; for it was not likely that nature should estrange the living thing from itself or that she should leave the creature she has made without either estrangement from or affection for its own constitution. We are forced then to conclude that nature in constituting the animal made it near and dear to itself ; for so it comes to repel all that is injurious and give free access to all that is serviceable or akin to it. As for the assertion made by some people that pleasure is the object to which the first impulse of animals is directed, it is shown by the Stoics to be false. For pleasure, if it is really felt, they declare vol. u o 193