Quintus, a Pythagorean philosopher, who flourished in the time of Augustus. He seemed formed to rise in the republic; but he shrank from civil honours, and declined accepting the rank of senator when it was offered him by Julius Caesar, that he might have time to apply to philosophy. It appears that he wished to establish a school at Rome, and that his tenets, though chiefly drawn from the doctrines of Pythagoras, in some particulars resembled those of the Stoics.

He soon found himself involved in many difficulties. His laws were tinctured with great severity, and in an early period of this establishment he found his mind so harassed, and the harshness of the doctrines which he wished to establish so repulsive, that he had nearly resolved to put a period to his existence.

Of the school of Sextius were Fabianus, Sotion, Flavius, Crassius, and Celsius. Of his works only a few fragments remain; and whether any of them formed a part of the work which Seneca admired so much, cannot now be determined. Some of his maxims are valuable. He recommended an examination of the actions of the day to his scholars when they retired to rest; and he taught, that the road to heaven was by frugality, temperance, and fortitude. He used to recommend holding a looking-glass before persons disordered with passion. He enjoined his scholars to abstain from animal food.