A miniature by Reginal Easton
[Bodleian Library, Oxford]

(1840)
A Painting by Richard Rothwell
[National Portrait Gallery]
Extract from a review of The Sexual Politics of Meat by Carol Adams
Dismemberment of a text can be achieved in a number of ways, including ignoring the text entirely, failing to acknowledge the vegetarian message in the text, or trivializing it, and by distorting the message so that it is consistent with and indistinguishable from the dominant discourse of meat. Adams argues that feminist literary critics and historians are among those who have dismembered such texts, and in using some of the same tools that patriarchy uses to silence feminists texts, these feminists have silenced some of their won feminist vegetarian sisters.
Mary Shelly's FRANKENSTEIN is a case in point. FRANKENSTEIN has received an enormous amount of critical attention over the past two decades from feminists and other critics, all of whom have neglected to explore the vegetarian themes in the novel. Frankenstein's creature is a vegetarian. Adams says: "The Creature's vegetarianism not only confirms its inherent, original benevolence, but conveys Mary Shelley's precise rendering of themes articulated by a group of her contemporaries whom I call `Romantic vegetarians'" (p. 109). The story "bears the vegetarian word," as Adams puts it, in a variety of ways: by alluding to the literal words of famous, historical vegetarians; by allowing fictional characters to allude to famous vegetarians; by translating vegetarian texts; by using language which reveals the function of the absent referent. Shelley grew up in an intellectual environment in which vegetarianism was much discussed and often adopted by such writers and activists as John Frank Newton, Joseph Ritson, and her father, William Godwin. Shelley's husband, Percy, authored two vegetarian texts, A VINDICATION OF NATURAL DIET and QUEEN MAB, and the Romantics with whom they kept company viewed radical politics and other unorthodox notions such as Republicanism as going hand-in-glove with their vegetarianism (p. 111).
Adams claims that feminist literary critics and historians have failed to explore the associations that Shelley and a number of nineteenth and twentieth-century pacifists, such as Olive Shriener and Anna Kingsford, made between flesh eating, domestic violence, and war. These woman saw the elimination of violence on the dinner table as a first and necessary step toward eliminating violence on the domestic "front," and ultimately between nations.
Extract from an article on an American University website (author unknown):
Another considerable influence on Mary Shelley and in turn the monster, was the works of Rousseau. Mary studied Rousseau early in her own intellectual development (Marshall, 182) and during the period that she composed Frankenstein (Feldman, 93-97). In Rousseau's Second Discourse is a discussion on the state of natural man or what Rousseau calls the "noble savage". Frankenstein's monster is an embodiment of this state of being developed by Rousseau, in which the monster first discovers himself and later the knowledge of language and the conventions of society. The monster's narration of his personal development and later acquisition of knowledge has been recognized by critics of the novel as a "noble savage whose early life in the forest (drinking at brooks, eating nuts and berries and not meat, sleeping under trees, encountering fire for the first time, acquiring language, and so on) conforms in general outline and specific details to the life of Rousseau's savage"(Marshall, 183).
Note: apparently Mary Shelley was also influenced by 'Observations on Man' by David Hartley and Ovid's Metamorphoses