Descartes' views on the differentiation between mind and body have given rise to many reflections on the interaction between these supposedly distinct substances. Looking at the correlations between Princess Elizabeth of Bohemia, it is evident that Descartes himself struggled to plausibly identify the interaction between the mental and material in relation to causality. This essay will examine Elizabeth's claims about the causal relationship between mind and body by explaining and investigating Descartes' distinction between the mental and the physical as separate substances, Elizabeth's concern with the problem of Descartes' interaction and response to these concerns. there are two fundamental types of distinct substances: material (physical thing) and mental (incorporeal, thinking thing) is a philosophical position consistent with the claims of theology that an independent sphere of existence, distinct from that of the physical world, is occupied by immortal spirits (Hart 1996) and may therefore have been developed to justify the existence of God. Describing the mind as an "extended and thinking thing" and the body as an "extended and non-thinking thing", Descartes insists in his 6th Meditation that even after great bodily changes, a material substance does not remain itself. only in a modified form. . As such, it follows that the basis of what makes that thing what it is must lie in a distinct unextended substance. Descartes goes on to explain the possibility of the mind existing without the form of a material body, as a substance whose essence is thought, and is therefore undoubtedly distinct from the physical. Although the two are ontologically distinct substances, the essential...... middle of paper ......ole. As Descartes begins in Principles, Part I: “But we also experience in ourselves certain other things, which must be referred neither to the mind alone, nor to the body alone. These arise, as will be clarified at the appropriate time, from the close and intimate union of our spirit with the body. For example, the movement of an eye can produce patterns of sensation in the mind and it is this combination of both mental and physical in humans that causes the perception of a chair (or any other view that we can see). As the mind acting on the body through voluntary action and the body on the mind through perception and sensation are constantly experienced, an interaction between the mental and the material is evident. Descartes argues that human beings possess the primordial notion of substantial union, but this is often confusing and misapplied..•