The object still exists as well, even if it only perceived inaccurately by the material world and by the sensations Mathematical proofs and mathematical calibrations are accurate, when correctly done, according to Descartes, because they can be proven by logic that the existence of such things exist with tools outside of the body. But although Descartes' Christian world of a non-deceitful god may have been persuasive to his readers, a contemporary reader might ask, what about when the body is affected by the mind -- for example, when one's heart pounds when the mind is nervous,...

This suggests a connection between mind and body that is less causal and easy to predict than suggested by Descartes, a connection that would be expanded upon more in later psychology and human biology.
Works Cited

Modern Philosophy. An Anthology of Primary Sources. Ed. By Roger Ariew and Eric Watkins. Indianapolis: Hackett Publishing Inc.