John Frank Newton (1770-?1827)

So long as men are compassionate to such a degree that they cannot hear a fly struggling in a spider's web without emotion it can never be reasonbably maintained that it is their natural impulse to wound and kill the dumb animals, or to butcher one another in what is called the field of honour. - The Return to Nature (as quoted in The Extended Circle by Jon Wynne-Tyson)
In 1812, through William Godwin's son, Shelley met John Frank Newton, the author of "The Return to Nature" which strongly advocated the vegetarian diet. Newton was a highly educated person who had formerly been at Christ Church College Oxford and intended to write three more books on vegetarianism. The Shelleys were influenced by his vegetarian views and adopted them in 1812. Later they admitted that their health had improved and that they felt much better. - extract from Shelley and Vegetarianism, A brief study of the English poet's attitude to vegetarianism by Mihaela Mudure of Romania