John Passmore claimed that there was no surviving textual evidence for ethically motivated vegetarianism in either ancient and medieval Catholicism or in the Eastern Churches. There were instances of compassion to animals, but no explicit objection to the act of slaughter per se. The most influential theologians, St Augustine and St Thomas Aquinas, emphasized that man owes no duties to animals. Although St. Francis of Assisi described animal beings with mystic language, contemporary sources do not claim that he practised or advocated vegetarianism.