I was early convinced in my mind that true religion consisted in an inward life wherein the heart doth love and reverence God the Creator and learns to exercise true justice and goodness not only toward all men but also toward the brute creation; that as the mind was moved on an inward principle to love God as an invisible, incomprehensible being, on the same principle it was moved to love him in all his manifestations in the visible world; that as by his breath the flame of life was kindled in all animal and sensitive creatures, to say we love God … and at the same time exercise cruelty toward the least creature … was a contradiction in itself.

John Woolman, 1772