This first book-length story and study of philosopher, activist, inventor, and philanthropist Lewis Gompertz--co-founder of both the Society for the Prevention of Cruelty to Animals (1824, ousted in 1832) and the Animals' Friend Society (1832-52)--charts his struggle against likely and unlikely enemies on behalf of other species, women, the poor, apprentices, prisoners, and slaves. Outraging fearful, elitist Christians, his classic Moral Inquiries on the Situation of Man and of Brutes (1824) reveals influences, tenets, and indeed his own situation in attempting to formulate and live by a rational morality for others' benefit, defying religious and structural forces that wanted far less. Power, class, philosophy, history, education, reform, and revolution all play their part in this account of his campaigning work and works (including Fragments in Defence of Animals and The Animals' Friend periodical), exposing the racist, sectarian rhetoric and scheming he endured at a defining moment. This attritional action, by which humane progress was obstructed and for more than a century fixed, is more disturbing than has been made widely detailed until now, in this much-needed, critical introduction.