Descartes' answer at the time was that deceptions are a result of our misuse of free will. Descartes is known as the father of the mind-body problem. He claimed that human beings are composites of two kinds of substances, mind and body. A mind is a conscious or thinking being, that is, it understands, wills, senses, and imagines. A body is a being extended in length, width, and breadth.
Minds are indivisible, whereas bodies are infinitely divisible.
Despite having different natures, Descartes thought that mind and body causally interact. The human mind causes motions in the body by moving a small part of the brain. Motions in that same part of the brain produce sensations and emotions. Ultimately Descartes thought that the mind or soul and body are united in a peculiar way, but the peculiar nature of this union cannot be explained. In the Passions of the Soul he suggested that the mind and body interacted through the pineal gland.