The mind cannot be understood to be shaped or in motion. The body on the other hand lacks in features such as privateness and intentionality, nor can the body understand or sense anything. The essence of body is extension and the essence of mind is thought, not vice versa. Descartes argues that he is a "thing that doubts, understands, affirms, denies, wills and refuses in addition to being capable of imagining and having sensory perceptions. These modes cannot be applied to non thinking things such as a stone. Only minds can have these attributes. Their principal attributes exclude each other therefore they can exist apart from each other and if they can exist apart from each other, then they are in fact distinct. Since the mind and body are logically different and lack identical properties, they must be ontologically different. Their states of existence are different from one another. .
Secondly, the mind and body are separate from each other because the body is divisible but the mind is indivisible and this is clearly stated by Descartes. "There is a great difference between mind and body, inasmuch as body is by nature always divisible, and the mind is entirely indivisible."(1980, p. 97) He states that if a foot or an arm is taken away from the body, one is aware that nothing has been taken away from the mind. The mind has not been affected by this division of the body. Since the body has extension in three dimensional space, it can be divided into specific parts. The mind on the other hand does not occupy space and therefore cannot be divided in the way that the body can. For example, the sound of a piano or the smell of roses are both states of mind and they cannot be divided. How is it possible to divide a smell or half a sound? Descartes believes that the body, by nature is always divisible. .
In addition, the mind and body are two separate and different substances due to observability.
