Instead, Plato's more philosophical characters argue that nous must somehow perceive truth directly in the ways gods and daimons perceive. What our mind sees directly in order to really understand things must not be the constantly changing material things, but unchanging entities that exist in a different way, the so-called "forms" or "ideas". However he knew that contemporary philosophers often argued (as in modern science) that nous and perception are just two aspects of one physical activity, and that perception is the source of knowledge and understanding (not the other way around).