 Dewey’s methodological lesson regarding instincts was twofold; first, one cannot premise an empirical science on unquestioned, metaphysical posits; even basic terms must be open to revision or deletion; second, strictly analytical methods using simple elements to build up complex behavior are often inadequate to explain the meaning of psychological phenomena. This lesson also applies to perception and sensation. Dewey attacked the view, common in his day, that a perception (1) was simply and externally caused, (2) completely occupied a mental state, and (3) was passively received into an empty mental space.