  Reid understands the Way of Ideas' error theory of the conception of a centaur: “The [proponent of the Way of Ideas] says, I cannot conceive a centaur without having an idea of it in my mind.... Perhaps he will say, that the idea is an image of the animal, and is the immediate object of my conception, and that the animal is the mediate or remote object.” Reid first responds that when he introspects he is aware of only one object of conception, not two. Second, the object of conception, he writes,