[142] Therefore we call music and grammar, and other pursuits, arts; for those also who are made perfect in them, as musicians, or grammarians, are called artists. But we call philosophy and the other virtues, sciences, and those who are possessed of the knowledge of them we call scientific; for they are prudent, and temperate, and philosophical, not one of whom is ever deceived in the doctrines of a philosophy which he himself has cultivated, any more than the artists, whom I have mentioned before, err in their speculations with respect to their indifferent arts.