I truly believe this statement to be true and as a proponent, would like to prove the argument based on some of Plato’s great works regarding the same.
Plato asserts that all the universal knowledge which human beings possess, is not acquired, it is already present in humans as we are “born” with the “knowledge of forms.” This knowledge, Plato states has been gained, before taking birth in the world, since the souls existed even before taking birth in the “Realm of Forms”, and this existence of the souls was forgotten at the time of birth. Claiming that “all wisdom is recollection”, Plato argues that the wisdom of the forgotten wisdom is recollected sporadically during the survival period in life.
Plato explains the difference in “how we know” and “what we know” by distinguishing between epistemology, which deals with the former, and metaphysics, which deals with the latter. Thus the epistemology of Plato elucidates the process of how the knowledge of the Forms, comes to human beings. Plato’s argument regarding epistemology is very clearly explained in the “Phaedo”, when Socrates, speaks to his friend Simmias, explaining to him the concept of equality, which is conceived with some kind of prior knowledge or perception. Socrates explains that a human sees two sticks or two stones which may or may not be equal in their appearances. Socrates argues that when two identical sticks or two identical stones are viewed by a person, how and why does that person compare them and decide whether they are equal or not. The point Socrates makes is indeed a valid one, for when a person looks at an object or two similar or dissimilar objects, what knowledge does the person have to decide about an aspect or feature that is different from the two objects- in this example- equality. There has to be some kind of prior knowledge that enables a person to deduce a property that does not in any way relate to the objects. It is this prior knowledge that the soul has, which comes from the Realm of Forms, which Plato states as epistemology. Plato elucidates Socrates’ argument that there has to be some prior knowledge about equality (in this example) in the human being which enables them to compare two objects and deduce whether they are equal or unequal.
He debates that all souls exist in the realm of Forms and as such have the knowledge, this being the first stage in the process of reincarnation of the soul. The second stage is that of birth as a human being. It is during this stage that the human loses or forgets all the knowledge which had been acquired when the soul was in another Form. The knowledge that the soul possessed is lost as all the memories of the previous existence is lost, as soon as the human being takes birth. During life, this knowledge is gained back with the help of senses which help in the recovery of knowledge. Thus all knowledge is merely a recollection of all that is already known to the human soul from the previous existence. In the third stage, which is death, the soul returns to the Realm of Forms, back to the original state from where it had taken birth. Plato believes that this process of existence in the Realm of Forms, birth as a human being and finally returning to the Realm is a continuous process and this is the theory of re-incarnation.
Thus, as a rationalist, Plato believes that the human mind is capable of acquiring knowledge without being dependent on all the other senses. The senses are only instruments or means with which the “innate” knowledge present in the human soul is recollected. Since knowledge already exists in the human soul, Plato believes in the theory of re-incarnation, a process that is ever occurring. The gaining and transfer of knowledge take place during the incessant circle of life when “innate” Knowledge is acquired from the Realm of Forms, lost at birth, and regained with the help of senses during the period of existence and the final stage of death in life and rebirth in the Realm of Forms.