Descartes shows that there is both a distinction and a union between the mind (a thinking, non-extended thing) and the body (an extended, non-thinking thing); however, this may not be clear, based on Princess Elisabeth's objection that questions how the mind (an immaterial thing) can move the body. According to Descartes, there are two finite substances that depend only on God to exist: the mind and the body. The mind is a thinking substance and its principal attribute is thought. Thought, alone, constitutes the mind's nature and essence. The body is an extended substance and its principal attribute is extension, that is, it occupies a three dimensional space. Extension is the nature and essence of the body. Descartes describes both a distinction and a relationship between the mind and the body. The ability to understand one thing, the mind, without another thing, the body, means that they are different from each other. In the Meditations, Descartes tells us that whatever is clearly and distinctly perceived is true. What can clearly and distinctly be understood about the mind is that it is a thinking, non-extended thing. What can clearly and distinctly be understood about the body is that it is an extended, non-thinking thing. When we observe the mind and the body like this, and exclude all of the things that are distinct from both of them, it is clear to see that they are distinct from each other. The principal attribute of a mind is thought, not extension, and the principal attribute of a body is extension, not thought. Their principal attributes exclude each other so they are different. Since the body is a non-thinking thing, it must be different from the mind, which is a thinking thing. In addition, a distinction can be seen between mind and body when considering their properties. The body, by its very nature, is divisible. According to Descartes, all bodies or extended things can be thought of as being easily divided into parts. For example, if a hand is removed from a body, the body continues to function and the mind of that body is not affected. The mind, by its very nature, is completely indivisible. Different faculties of the mind (understanding, intellect, perception) are not considered different parts of the mind but instead are considered as one, whole thing. They work together to create one, whole mind. The mind is something single and complete. If the mind could be divided, there could exist more than one "I", but this is contradictory. There is only one "I" and therefore, the mind is indivisible. Since the nature of the body and the nature of a mind are contradictory (divisible and indivisible, respectively), it follows that they are different things. This leads us to the relationship between the body and the mind. The body and the mind, though they are distinct, are united. They are joined to each other and are present to each other. They constitute one single thing. Descartes gives one proof of this. When the body is hurt, the mind, were it alone, would perceive this hurt with the intellect only. But, since the mind and the body are one thing, the mind feels pain as well. There exists a relationship between the mind and the body that causes them to act on each other. When the body is hurt, the pain is distributed throughout the nerves in the body and extended into the brain. This affects the mind with a sensation of pain. The mind then moves the body away from the cause of pain. For Princess Elisabeth, the relationship and distinction between the body and the mind is not perfectly clear. She objects to Descartes account by stating that it does not make sense that the soul/mind (a thinking thing only) can move the body. To Elisabeth, contact and extension are required for movement but Descartes excludes extension from his notion of the soul (or mind). She is not convinced that the body can be pushed by something immaterial. It is easier for her