Thrasymachus, a sophist said, was convinced that law and justice was not only the expression of domination of those in power, who through these procedures could do what suited them. Carneades (school skeptical), which held that man's natural instinct was always looking to fill their own interests, considered justice as crazy as it meant "the sacrifice of personal advantage in favor of a purely imaginary ideal." Others, like Protagoras, who point out as a precursor of positivism legal, radically determined that "man-made rules were mandatory and apply regardless of its moral content" 1. But the vast majority of thinkers adopted doctrines that accept the existence of a natural law as such "certain elements in human nature which are the same in all times and all peoples." Heraclitus of Ephesus (535 to 479 BC) conceived of the universe as an "eternal flow" as a constant and perpetual evolution where everything is subject to change. But that evolution was not seen as something that was not due to higher nature rules, unless the contrary thought he was first harmonic and second run for a reason which made ordering a presence throughout, even in the laws enacted by man. That reason, "ordering" and "creator" was, therefore, the source of all rules governing the conduct and beings. Hippias divided the law in written and unwritten saying the first was due to economic situations, while the second was dictated by the gods themselves and therefore force uniformly across all latitudes. Pythagoras then construct the first and incipient theory of justice, a point of first importance in the case of natural law.