In Plato's mind, the body is an anchor which holds the soul from enlightenment. That which we know (as we will discuss later) we knew before we had the body and it is only recollection of this knowledge that allows us to know anything while we are in the body. We will now discuss the application of this idea of Forms and the separation of the same from sensible particulars by discussing Plato's idea of "Two Worlds," or being and partaking. Being does not mean the same thing as partaking is not explained by and does not explain its essence. In fact, Plato postulated that is X lacks essence, it can fail to be. An example given is that of beauty. Beauty is beautiful, and other things become beautiful by partaking in what is beautiful. The question then comes whether the partaking is then dependent on the being. In what Plato uses as demonstration of the immortal soul, when being is confronted with its opposite, the being must then withdraw or die. If the beings do withdraw and exist apart from the forms, then the individuality then exists by particulars, which Plato believed were separate from forms.

In moving from the metaphysical to the epistemological, we understand that Plato believed that knowledge exists, and attempts to determine what makes knowledge possible. To Plato, Forms are knowledge. Souls are knowledge. If so, and if Forms do not exist within the physical world, then is it possible that knowledge also does not exist within the physical world? Plato, in Republic opines that Forms are related to one another, and this knowledge is therefore proof of existence. If knowledge is proof of existence, then knowledge must be instinctive and innate (one cannot be without knowing) but this knowledge is deep seated and not necessarily immediately recalled. Plato theorized that knowledge was present before...

The knowledge which was present before birth is in itself a Form, called "The Form of the Good." Plato believed that before we are born we retain a perfect knowledge of everything and when we learn we simply recall that which was already known. Plato uses the sun as a metaphor for the "Form of the Good," the sun being the ultimate form of light and that which allows us to see all things. That which we can see we can know.
Plato goes on in the Republic to state the goal of human development is the ultimate knowledge of forms acquired via the memory and accessed via a quick mind and persistent study. This lifelong effort would appear to exclude most of us from ever being able to achieve knowledge or enlightenment. The cave allegory is used here, in which Plato believes that only those who have been able to climb out of a cave and look at the sun (the Form of Good and symbolic of knowledge) are fit to rule above others. Ultimately, the middle years of Plato's work show Plato beginning to answer some questions he formulated during his years with Socrates, and moving on beyond the thinking and teachings of his master.

Bibliography

Melchert, Norman (2002). The Great Conversation: A Historical Introduction to Philosophy. McGraw Hill.

Vlastos, G., Platonic Studies (2nd ed., Princeton, 1981

Allen, R.E., 'Participation and Predication in Plato's Middle Dialogues,' in id. (ed.), Studies in Plato's Metaphysics: 43-60

Drede, D. 'The Final Proof of the Immortality of the Soul,' Phronesis, 23(1978): 24-41

Moore, Edward (2007). Plato. Philosophy Insights Series. Tirril, Humanities-Ebooks

Szlezak, Thomas a. (1999). http://books.google.com/books?id=x34szlJIRIgC" Reading Plato. Routledge