"I think therefore I am." Man wills, refuses, perceives, understands, and denies many principles.  As explained by Rene' Descartes, man is a thinking thing, a conscious being who truthfully exists because he is certain that it is so. All that man perceives is internally present and not external to him or his mind.  The focal point of the third meditation that must be dealt with is: Can one perceive or confirm the existence of an idea or object that is external to him mainly - God?
	There are three ways, Descartes explains, that one may come to the conclusion of an objects existence.  The first is through nature.  The second is through feeling an object independent of one's will, for example; heat and cold.  The third, and most elaborated upon is the point of cause and effect, or more simply, the objective reality of an idea. We will primarily deal  with the third reason of cause and effect.
	Descartes brings some examples to demonstrate his cause and effect theory.  More importantly, is the logic that lies behind the actual theory. The rationale that an object will have an effect is only if it stems from a legitimate cause.  A stone, for example, cannot be perceived accurately if there isn't an initial idea   preceding with equal or superior properties in one's intellect.  The mind generates ideas and develops reality through previous schema or beliefs as Descartes states: " And although an idea                           may give rise to another idea, this regress                        cannot, nevertheless, be infinite;we must in                       the end reach a first idea, the cause of which                       is, as it were, the archetype in which all the                       reality  that is found objectively in these                        ideas is contained formally."  


	Additionally, properties such as color, sound, heat, and cold are too complex in their nature for Descartes to determine whether they are true or false.  In other words, are the ideas that one has about a property  true or false?  Consequently, Descartes concludes that there is a common element between examples like the stone and the cold.  The cold portraying the unreal or false object and the stone as a true object.  He contends that they both contain "substance" like man himself, and are therefore similar.  
	The only difficulty that arises is the consideration of God's existence.  There is no substance or idea for the notion of God to originate from.  The valid question that Descartes asks is: Is it conceivable that a finite being have the idea of an infinite existence?
	We can understand from  Descartes writings that he believes in a God.  God is unspeakably great, eternal, independent, and all knowing.  What Descartes deduces is that the nature of an infinite  existence cannot be comprehended by a finite being.  Subsequently, by the fact that he believes there is a God is proof for his existence. The idea was placed there by an outside factor. He further states that if man is independent of all other existence  then he has the potential to reach  to become infinite. This in turn, lead Descartes to say  that if he was the author of his own being and independent  of all existence, then he would be God.  By that matter, it is all these points collectively that indicate to Descartes that he is dependant on another being, that is a God.
	It can be argued, very briefly, that Descartes assertion about God is slightly contradictory.  As I stated earlier, an object is perceived in the mind as long as there are equal or superior properties in the mind. His rests his whole argument on the basis that one cannot fully grasp or fathom the existence of God logically.  It is obvious that his perception is doubtful in the first place.  There is a lot more material to be covered before I can honestly sever Descartes' whole argument, but this is my opinion on the third meditation.