In the last part of the fifth century B. C., critical skepticism became universal. In religion the anthropomorphism of the Epic passes under ridicule. Critias declares that the gods are the invention of shrewd statecraft. In literature the Epic, in which the gods interfere in all human details, yields to the naturalistic descriptions of Herodotus and Thucydides, and to the personal note of lyric and satirical poetry. More important than all was the change of attitude toward the laws. Instead of the law having a divine authority, the individual placed himself above it and sat in judgment upon it. The tribal conception of guilt, that when a member of a tribe sinned the whole tribe would suffer at the hands of the gods, had given way at the time of the Persian Wars to that of personal responsibility and retribution. It was noted that laws change in the same state, that they differ in different states, and that moral customs have a great variety. All laws seem therefore to be made by man, and the question then arose, Is there any law which has universal validity? Is there any real _prius_ or “Nature” of laws? In the Anthropological Period, the important question was about the real _prius_ or “Nature” of human institutions, just as in the Cosmological Period the question was about the real _prius_ or “Nature” of the world of physical phenomena. Yet the question of the Anthropologists was a part of the Cosmological problem. The Cosmologists had called the real _prius_ or “Nature” (φύσις), that which ever remains like itself, and it is now asked if “Nature” in itself contains any unchanging and eternal politico-moral law. The contrast is thus drawn for all time between natural law and statute law, and the distinction dominates this period. Human legal institutions were regarded as only makeshifts, and often even as contradicting the divine law. The conflict between natural or divine law and human law appears worked out in the _Antigone_ of Sophocles.