On the Impropriety of Killing Living Beings for Food

If, however, some one should, nevertheless, think it is unjust to destroy brutes, such a one should neither use milk, nor wool, nor sheep, nor honey. For, as you injure a man by taking from him his garments, thus, also, you injure a sheep by shearing it. For the wool which you take from it is its vestment. Milk, likewise, was not produced for you, but for the young of the animal that has it. The bee also collects honey as food for itself; which you, by taking away, administer to your own pleasure. 

This excerpt introduces the notion that humans are unjustly taking the lives of other organisms and in doing so, humans are killing something of value. Porphyry criticizes how human greed takes away from the natural ecosystem. Porphyry was vegetarian and an advocate for vegetarianism based on both religious and ethical grounds. Porphyry encouraged respect for all living species and abstinence from flesh eating. He wrote other books promoting an awareness of the disorder wrought about by prerogative human consumption on the natural world. 

Porphyry uses empathy as a tool to validate the emotions of animals and how humans use them for our personal gain. Porphyry also believed that "if all men conceived rightly, there would be no need of fowlers, or hunters, or fishermen, or swineherds." He goes to say that man should be independent of meats and that to be intellectually capable, to philosophically think, man should adopt a vegetarian diet. This is significant in terms of vegetariansim because Porphyry describes that a humble and worthy man should be able to resist temptations and such luxuries of meat. 

A vegetarian diet (although most likely negatively viewed) also reflected a person's respectable identity as a philosopher who had the will to self-discipline themselves rather than succumb with the "normal" mass of humanity.