The essay on Progress in Virtue is one of Plutarch’s polemics against the Stoics, and is directed mainly against two of the doctrines of the Stoic philosophy. The first is that the wise man alone is virtuous, and that wisdom with attendant virtue is a sudden acquisition with no preliminary stages; the second is in a way the corollary of the first, since, if a man is not perfect (i.e. wise), it may be argued that it matters little how trivial is his imperfection and whether his faults be great or small. He that offendeth in one point is guilty of all.

Against such doctrines as these Plutarch’s strong common sense revolts, and he endeavours to show not only that ethical advance is possible, but that there are plenty of signs by which it can be recognized.

The essay is addressed (or dedicated) to Q. Sosius ¹ Senecio, one of Plutarch’s numerous Roman friends, who was twice consul in the early years of Trajan’s reign. It was at his request that Plutarch composed the Symposiacs, in which his name frequently appears, and to him are inscribed also the parallel lives of Theseus and Romulus, Demosthenes and Cicero, and Dion and Brutus. Plutarch had been with him much in Rome, and he had visited Plutarch in Greece. It is doubtless the same Sosius whom the younger Pliny addressed in two letters (i. 13 and iv. 4) which have come down to us. a So spelled in the best mss. of Pliny and in inscriptions.