All moral/religious commands that we encounter in ancient societies, like “Know thyself”, “be prudent” or “be frugal”, can be seen as the manifestations of virtues of “temperance” or “practical wisdom”. From the ancient civilization of China to the Sumerian and Egyptian civilizations, ancient wisdom contains innumerable examples of this virtue of temperance. In the history of the concept of temperance the practice of Ionian philosophers which can be described as wisdom grounded on knowledge constitutes a significant phase. However, sages-philosophers of the first period of philosophy, more accurately, of the period of philosophy of nature, investigate human being not directly as it is in itself but through the investigation of nature and as a part of nature. While investigating the cause of change and manifoldness in nature, they tried to find an order and measure in it. This endeavor was accompanied by the secret awareness of the investigator that the measure which he was seeking after was in fact himself; given that all Ionian philosophers were committed to the command “Know thyself” inscribed at the pediment of the Temple of Apollo at Delphi. Yet, reflecting on the command merely philosophically and the turn of philosophy entirely towards human being become possible only with Protagoras and Socrates (Plato). Via questioning human being, social and cultural life are included in the field of problems as well. It can be affirmed that the relation of the command “Know thyself” to the concept of temperance becomes through Protagoras’s ideas “Human is the measure of all things” on the one hand and through Socrates’ ideas “God is the measure of the all things” on the other. Hence the main purpose of this article is to examine, through Protagoras and Socrates’ ideas, different manifestations of the command “Know thyself” and the virtue of temperance in epistemological and ethical realms.