Thomas Aquinas, at the very time when an infusion of popular elements was modifying feudalism, and it helped to emancipate political philosophy from despotic theories and to confirm it in the ways of freedom. The three generations of the Socratic school did more for the future reign of the people than all the institutions of the States of Greece. They vindicated conscience against authority, and subjected both to a higher law; and they proclaimed that doctrine of a mixed constitution, which has prevailed at last over absolute monarchy, and still has to contend against extreme Republicans and Socialists, and against the masters of a hundred legions. But their views of liberty were based on expediency, not on justice. They legislated for the favoured citizens of Greece, and were conscious of no principle that extended the same rights to the stranger and the slave. That discovery, without which all political science was merely conventional, belongs to the followers of Zeno. The dimness and poverty of their theological speculation caused the Stoics to attribute the government of the universe less to the uncertain design of gods than to a definite law of nature. By that law, which is superior to religious traditions and national authorities, and which every man can learn from a guardian angel who neither sleeps nor errs, all are governed alike, all are equal, all are bound in charity to each other, as members of one community and children of the same God. The unity of mankind implied the existence of rights and duties common to all men, which legislation neither gives nor takes away. The Stoics held in no esteem the institutions that vary with time and place, and their ideal society resembled a universal Church more than an actual State. In every collision between authority and conscience they preferred the inner to the outer guide; and, in the words of Epictetus, regarded the laws of the gods, not the wretched laws of the dead. Their doctrine of equality, of fraternity, of humanity; their defence of individualism against public authority; their repudiation of slavery, redeemed democracy from the narrowness, the want of principle and of sympathy, which are its reproach among the Greeks. In practical life they preferred a mixed constitution to a purely popular government. Chrysippus thought it impossible to please both gods and men; and Seneca declared that the people is corrupt and incapable, and that nothing was wanting, under Nero, to the fulness of liberty, except the possibility of destroying it. But their lofty conception of freedom, as no exceptional privilege but the birthright of mankind, survived in the law of nations and purified the equity of Rome.