There is no real difference between space, or internal place, and the corporeal substance contained in it. The only difference lies in the way in which we are accustomed to conceive of them.

Since body is nothing but extension, Descartes claims that there is no difference between body and space. Bodies are not in space, as we normally believe; space is body. The only difference between space and the things we call bodies is that space has not sensible qualities such as color, hardness, smell etc. This is one of the central tenets of his physics.

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