who founded the Porch. The later heads of the school, as _Panætius_, the friend of the younger Scipio (his famous work De Officiis, Cicero has elaborated in his treatise of the same name), and _Posidonius_, may be classed with Cicero, Pompeius, and others, and were eclectic in their teachings. The Stoics have connected philosophy most intimately with the duties of practical life. Philosophy is with them the practice of wisdom, the exercise of virtue. Virtue and science are with them one, in so far at least that they divide virtue in reference to philosophy into physical, ethical, and logical. But though they go on according to this threefold division, and treat of logic and physics, and though they even rank physics higher than either of the other sciences, regarding it as the mother of the ethical and the science of the Divine, yet do we find their characteristic standpoint most prominently in their theory of morals. 1. LOGIC.—We have already said that it is the breach between subject and object, which forms the basis of all post-Aristotelian philosophy. The beginning of this philosophy of subjectivity is found with the Stoics. The feature most worthy of notice in their logic, is the striving after a subjective criterion of the truth, by which they might distinguish the true representation from the false. Since they limited all scientific knowledge to the knowledge of the senses, they found this criterion in that which was evident in the sensuous impression. They conceived that they had answered the whole problem, in affirming that the true or conceivable representation reveals not only itself, but also its object: it, they said, is nothing else than a representation which is produced by a present object in a manner like itself.