5.

It is strange that we do not perceive the force of gravity directly; we understand it only through its effects -- it is an idea, a second-order perception, but it is first-order in the extent to which it structures our lives.

Religious conceptions like God or moral conceptions like Truth or Justice function in precisely the same manner as the idea of Gravity. The only difference between these conceptions and the notion of gravity is only that there is no connection between religious and moral conceptions and sense experience. Psychologically, however, their function is identical.