As regards the Physics of the Stoics, we may in the first place say that it does not contain much that is peculiar to itself, since it is rather a compendium of the Physics of older times, and more especially of that of Heraclitus. However, each of the three schools now being dealt with has had a very characteristic and definite terminology, which is more than can be altogether said of the philosophy of Plato and Aristotle. Thus we must now make ourselves familiar with the particular expressions used and with their significance. The following is the essence of the Physics of the Stoics: The determining reason (λόγος) is the ruling, all-productive substance and activity, extended throughout all, and constituting the basis of all natural forms; this preponderating substance, in its rational effectuating activity, they call God. It is a world-soul endowed with intelligence, and, since they called it God, this is really Pantheism. But all Philosophy is pantheistic, for it goes to prove that the rational Notion is in the world. The hymn of Cleanthes is to this effect: “Nothing happens on earth without thee, O Dæmon, neither in the ethereal pole of the heavens, nor in the sea, excepting what the wicked do through their own foolishness. But thou knowest how to make crooked things straight, and thou orderest that which is without order, and the inimical is friendly to thee. For thus hast thou united everything into one, the good to the evil; thus one Notion (λόγος) is in everything that ever was, from which those mortals who are evil flee. How unhappy are they, too, who, ever longing to possess the good, do not perceive God’s universal law, nor listen thereto, the which if they but obeyed with reason, (σὺν νῷ) they would attain a good and happy life!”[127] The Stoics thus believed the study of nature to be essential, in order to know in nature its universal laws, which constitute the universal reason, in order that we might also know therefrom our duties, the law for man, and live conformably to the universal laws of nature. “Zeno,” according to Cicero (De nat. Deor. I. 14), “holds this natural law to be divine, and believes that it has the power to dictate the right and prohibit what is wrong.” Thus the Stoics desired to know this rational Notion which rules in nature not altogether on its own account; and the study of nature was consequently to them rather a mere matter of utility.