For ethical exploration of the good, the bad, and the indifferent. The art of life and critique of the perceptions of dogmatists. For mathematicians Lessons, according to Sextus, are the particular domains of knowledge, the sciences. With this work, the skeptical philosopher addresses those who showed little or no interest in traditional philosophical problems regarding nature, logic, or ethics. For grammarians Sextus, without taking sides in favor of one or the other linguistic theory, challenges the basic grammatical concepts (and terms), proving them unsubstantial, and attempts to undermine the certainty of "scientific" discourse with doubt.