 Little is known for certain about the details of Pyrrho's philosophy and how it may have differed from later Pyrrhonism.Most of what we know today as Pyrrhonism comes through the book "Outlines of Pyrrhonism" written by Sextus Empiricus over 400 years after Pyrrho's death.Most sources agree that the primary goal of Pyrrho's philosophy was the achievement of a state of ataraxia, or freedom from mental perturbation, and that he observed that ataraxia could be brought about by eschewing beliefs (dogma) about thoughts and perceptions.