The matter comprising a substance, for example, is mutable. Therefore matter is a potentiality. This is connected to the idea of passivity , and may be considered to be a cornerstone of the idea of a passive intellect. Aristotle described the process of the development of the intellect, and in so doing constructed a hierarchy of intellectual function. First and most basically, the blank slate of the new mind is subjected to sensation.
Sensations lead to memory, which in turn lead to experience.
Experience is the beginning of wisdom, and of associating perceived phenomena. It can lead to art, which entails a knowledge of the method by which things work. Highest in the scale is theoretical knowledge, which allows for understanding of the deepest principles of reality and of the prime causes. Leibniz' monad is defined partially by its perception. Granted, for Leibniz the term perception represents something beyond sense perception as we think of it.