in 1806, with his eye on a teaching post at the royal academy, bell published his "essays on the anatomy of expression in painting" (1806), later re-published as "essays on the anatomy and philosophy of expression" in 1824. in this work, bell followed the principles of natural theology, asserting the existence of a uniquely human system of facial muscles in the service of a human species with a unique relationship to the creator, ideals which paralleled with those of william paley. after the failure of his application (sir thomas lawrence, later president of the royal academy, described bell as "lacking in temper, modesty and judgement"), bell turned his attentions to the nervous system.