Porphyry's On Abstinence from Killing Animals is one of the most interesting books from Greek antiquity for both philosophers and historians. In it, Porphyry relates the arguments for eating or sacrificing animals and then goes on to argue that an understanding of humans and gods shows such sacrifice to be inappropriate, that an understanding of animals shows it to be unjust, and that a knowledge of non-Greeks shows it to be unnecessary.
There are no Neoplatonist commentaries on Aristotle's Ethics from the period AD 250-600. Thus, although this work is not a commentary on Aristotle, it fills a gap in this series by going to the heart of ethical debates among Neoplatonists around AD 300, and revealing one ascetic Neoplatonist's view of the ideal way of life. It also records rival positions taken on the treatment of animals by Greek philosophers over the previous six hundred years.
Porphyry's parents were Phoenician, and he was born in Tyre. His parents named him Malchus ("king") but his teacher in Athens, Cassius Longinus, gave him the name Porphyrius ("clad in purple"), possibly a reference to his Phoenician heritage, or a punning allusion to his name and the color of royal robes.
Porphyry of Tyre (Greek: Πορφύριος, Porphyrios, AD c. 234–c. 305) was a Neoplatonic philosopher who was born in Tyre. He edited and published the Enneads, the only collection of the work of his teacher Plotinus. He also wrote many works himself on a wide variety of topics. His Isagoge, or Introduction, is an introduction to logic and philosophy,and in Latin translation it was the standard textbook on logic throughout the Middle Ages. In addition, through several of his works, most notably Philosophy from Oracles and Against the Christians, he was involved in a controversy with a number of early Christians, and his commentary on Euclid's Elements was used as a source by Pappus of Alexandria. (Wikipedia)
My other exposure to Porphyry comes from his On the Cave of the Nymphs and On the Life of Plotinus. I found this book fascinating and stimulating to the imagination. Book 3 is undoubtedly the one which speaks most to our modern sensibilities, as it deals with animal cognition, arguing that animals are rational, have lives of their own, and are related and comparable to (and in some respects surpass) humans. The conclusion being that animals should not be killed, cut up, and eaten by us in order to satisfy our desires! I found Book 3 very beautiful, and the prose in Gillian Clark's translation really flowed as Porphyry goes on marvelously and with a palpable sense of wonder about the amazing and varied gifts of animals and their relationships with human beings and with each other. Of course Porphyry discusses many other issues, including the nature and history of sacrifices to the gods, how the earliest and purest sacrifices did not include animal sacrifice, and the virtues of abstinence and self-restraint for sages and lovers of wisdom. He also discusses and makes reference to aspects of Neoplatonic metaphysics and cosmology, including: the soul's relation to the body, the nature of death, and the good and evil daimones (all of which I found very fun and interesting). Some parts dragged but on the whole I found it a worthwhile read and a great window into the history of vegetarianism and animal rights as a tradition.
Clarke's modern translations are getting rave reviews. I can't judge that, but I can say it's a flowing, readable, but still recognizably ancient text. Porphyry's discussion and arguments are worth considering and (with the exception of sacrifice) contemporary for us. It has re-challenged my beliefs about my relation to non-human life, and anyone thinking that through for yourself could learn from it. Plus there's something kinda lovely about Porphyry's writing.