Because human beings are rational, rather than instinctive beings, we are constantly engaged in the process of learning and acquiring knowledge.

The infant is born essentially without knowledge. He or she may have certain traits or tendencies, and may even react with some degree of instinctive behaviour, but the infant knows nothing of his world.

From birth (and perhaps before) the individual begins a process by which he or she begins to learn, to acquire knowledge about the objective universe in which he or she finds him or her self.

First, the infant begins by perceiving the existence of certain phenomena (facts), in the world around him. He or she does not perceive everything, of course. Some things, perhaps many things, will escape his or her notice.

Of the things the infant does perceive, he or she begins to identify, within the limits of his or her perception.

If the infant is lying in a crib, he or she may perceive the sides of the crib. He will have no knowledge of what is under the crib, because he has no way of perceiving it, and there is no way of communicating that part of reality to him.