These touches of feeling, slight as they may appear, indicate, I think, a vein of sentiment such as we should scarcely have expected to find coexisting with the gigantic slaughter of the amphitheatre. The progress, however, was not only one of sentiment—it was also shown in distinct and definite teaching. Pythagoras and Empedocles were quoted as the founders of this branch of ethics. The moral duty of kindness to animals was in the first instance based upon a dogmatic assertion of the transmigration of souls, and, the doctrine that animals are within the circle of human duty being thus laid down, subsidiary considerations of humanity were alleged. The rapid growth of the Pythagorean school, in the latter days of the Empire, made these considerations familiar to the people.(372) Porphyry elaborately advocated, and even Seneca for a time practised, abstinence from flesh. But the most remarkable figure in this movement is unquestionably Plutarch. Casting aside the dogma of transmigration, or at least speaking of it only as a doubtful conjecture, he places the duty of kindness to animals on the broad ground of the affections, and he urges that duty with an emphasis and a detail to which no adequate parallel can, I believe, be found in the Christian writings for at least seventeen hundred years. He condemns absolutely the games of the amphitheatre, dwells with great force upon the effect of such spectacles in hardening the character, enumerates in detail, and denounces with unqualified energy, the refined cruelties which gastronomic fancies had produced, and asserts in the strongest language that every man has duties to the animal world as truly as to his fellow-men.(373)