Magnitude or extension in length, breadth, or depth, I do so perceive; I have before remarked that it is only in judgments that falsity, properly speaking, or formal falsity, can be met with, a certain material falsity may nevertheless be found in ideas, i.e. when these ideas represent what is nothing as though it were something."(Descartes) On the contrary, through judgment or reason the material can be very well apprehended. Thus, Descartes disclaims that the essence of wax or of any other material object can be grasped and understood through either mere sensuous perception or through the imagination. It is only the mind or reason that can tell us what wax is. His main arguments against sensuous perception only is that the wax is likely to change some of its physical qualities, such as color or form for instance, but we still know what it is. Likewise, the imagination cannot follow all the changes or the process...

As such, the mind remains the actual locus of perception and relevant understanding.
The essence of things is thus only perceived by the mind. According to Descartes, we have the essence of something when we remove all the mutable qualities about it. Thus, Descartes theorizes his famous body and mind duality by evidencing that these two are not unitary in their perception. The body offers only separated or divided information, as it comes from the different senses, according to Descartes. The mind however is a unitary whole, able to perceive and understand even that which is not immediately given to the senses. Needless to say, reason becomes thus the most important attribute of man, the thing that distinguishes him from the other animal species.

Works Cited

Descartes, Rene. Meditations. http://www.sacred-texts.com/phi/desc/med.txt