I thoroughly enjoy reading about the ancient Greek philosophers, my favorites being Plato and Demosthenes. It took me a while to find something original to write about Plato as there are many superb hubs already residing on hubpages' servers. His theory of forms is of great interest to me and there is a wealth of information available for research as it remains one of the most famous philosophical theories today.

Down through the centuries, many philosophers, theologians and artists have been struck by the thought that what we seem to see around us is not the 'ultimate' reality, but that the real world is somehow hidden. They have suggested that, if we could only pull back the curtain that divide us from this reality, we would be confronted by something extraordinary.

Plato's theory of forms is one of the most vivid and dramatic examples of this kind of thinking. The theory has had a powerful effect on the shape of philosophical thinking over the last two millennia. While comparatively few philosophers might now be described as Platonists, Plato's theory remains endlessly fascinating, and continues to be a source of not only philosophical, but also religious and artistic inspiration.

What is the theory of forms? According to Plato, those objects that we seem to see around us--chair and tables, trees and mountains, ants and planets--are not what is ultimately real. They are mere shadows or reflections of the truly real objects--the forms.

Take trees, for example, According to Plato, each particular tree is a fleeting reflection of a form: the form of 'tree'. There is also a form of the table, a form of the chair, and so on. These forms differ from the the particular tables and chairs we observe around us in a number of important ways:

• The forms are are more real than are the particulars that 'partake' of them. Indeed, particular trees derive what existence they have from the form of the tree. If there was no form of the tree, there could be no particular trees.

• Unlike their particular instances, the forms are perfect. Again, consider trees. No particular tree is ever entirely perfect. It always possesses some flaw. The form of the tree, by contrast, is perfect in every respect.

• Plato points out that particulars often exemplify both a property and its opposite. Take equally, for example,. No two particulars are ever perfectly equal. Two glasses of water will never exhibit perfect equality. There will always be some inequality present: one glass will contain a tiny bit more water than the other, or will be of a microscopically different shape. Or take the property of being small. A particular that is small--an ant, say--is always small in a qualified way. While an ant is small compared with us, it is large compared with a speck of dust. So again, we find that when it comes to particulars, smallness is always present with its opposite: largeness. Plato believes that the forms of smallness and equality, by contrast are always unqualifiedly so. There is no equality, nor is any largeness present in the for of the small.

• The forms are eternal and unchanging. Particulars come and go. A particular tree grows, then dies, then rots and is gone. The form of the tree, by contrast, is eternal. It neither comes into being or ceases to be. Nor do the forms change. Our ideas change, of course. Take our idea of beauty--it is constantly evolving. Not so long ago, being pale and buxom was all the rage. Now being thin and tanned is considered more desirable. According to Plato, while fashions may change, true beauty does not. The form of beauty is both changeless and timeless.

If Plato's forms exist, where are they? They are located within the physical world. Nothing within sensible reality is ever perfect and everything is in a constant state of change. So the forms, if they exist, must exist on a higher plane. The forms, according to Plato, constitute an eternal, changeless, perfect reality--a domain more real than that revealed by our senses.

Plato argues that not only is the realm of the forms true reality, but that ultimately, the forms are also the only source of knowledge. True knowledge, argues Plato, cannot change. Our beliefs change, of course. We might believe that Paris is in Germany, and then later on believe it is in France. But genuine knowledge can't change in this way.

Plato argues that if knowledge cannot change, then true knowledge must be of what is unchanging. As the world revealed to the senses is in a constant state of change, it follows that the senses cannot provide us with knowledge. True knowledge can only be of the unchanging realm of forms.

So how do we acquire knowledge of this higher realm? According to Plato, each of us possesses an immortal soul. This soul was once acquainted with the realm of the forms. Because we were once presented with the forms, we are now able dimly to recollect what they are like.

So we are, if you like, born with knowledge of the forms. The knowledge is innate. But it is not easily accessed. In order to begin to recollect more clearly, we need to engage in philosophical inquiry. We must shun the senses (which reveal only an illusion) and apply our powers of reason. It is philosophical inquiry that ultimately produces true knowledge: knowledge of forms.