If a man's aspiration towards a righteous life are serious, his first act of abstinence is from animal food, because it is plainly immoral as it requires an act contrary to moral feeling, ie., killing - and is called forth only by greed
Animal Liberation
I had been vegan for a few years, done some volunteering for Animal Liberation Queensland, and read some of Peter Singer's other works before I finally read his classic Animal Liberation.
I didn't really see why I needed to read it, after all, I was vegan and very much believed in Animal Liberation. As fate would have it I was given two copies of the book in the same week, and although a sceptic I believe in fate just enough not to tempt very obvious expressions of its desires so I had little choice but to start reading.