On their physical principles, the moral principles of the Stoics depended. Conceiving themselves to be part of universal nature, that their souls were part of the divinity which actuated matter, they held themselves in some measure to be gods. In human life therefore they must follow nature, of which they formed part. But then this _nature_ was not this or that man’s natural leaning, but the laws of fate and the universal course of things, from which resulted the unsuitableness of certain courses, and the excellence of others. To be conformed to the laws of the universe, of which they formed an essential part, was the ultimate end of life. Every man conforming to these laws is happy, notwithstanding external evils. Every man’s happiness, then, is in his own power; he is a god to himself in some measure. To live according to his true nature is to live godly; godly life is virtue. This is itself true happiness, independently of pleasure in the common acceptation of the term; because the supreme good is to follow what the law of nature points out as being good. Virtue having its seat in the soul, outward circumstances cannot reach the good man. As he can distinguish good from evil, he is wise; and this suffices for him. External things, forasmuch as they cannot reach him, can neither increase his happiness or cause him misery. Even torture cannot move him, because it cannot reach his inner, true nature. There is no distinction between different virtues as to degree, because they owe their existence to their accordance with nature. All vices are equal in degree, because they run counter to the one law of virtue. These seem to have been the principal features of Zeno’s teaching. His morality partook of the evil of its origin. It was essentially artificial. Little regard was paid to real nature in the pursuit of what was called natural law: there was little common sense, oftentimes, in the ideas set forth under pretence of philosophy.