Descartes created the mind-body divide and claimed these to be two different substances—the extended substance (res extensa) and the thinking substance (res cogitans). However, with the progress in science (and attempts to subsume thinking under matter), the distinction between mind and body gets hazier by the day. What is the difference between matter and spirit, if any at all?
In the Srimad Bhagavatam, a Vedic literature widely regarded as the culmination of Vedanta (which is in itself considered the conclusion of all knowledge), Sage Kapila elaborates the Sankhya theory of material nature to his mother Devahuti and concludes (SB 3.32.32): Philosophical research culminates in understanding the Supreme Personality of Godhead. After achieving this understanding, when one becomes free from the material modes of nature, he attains the stage of devotional service. Either by devotional service directly or by philosophical research, one has to find the same destination, which is the Supreme Personality of Godhead.
A common argument against the mind-body duality is that mind is an epiphenomenon of chemical reactions in the brain much like the fluidity of water is a consequence of molecular interactions. This argument seems quite appealing because if we reduce water to its molecules, we don’t see fluidity in each molecule; fluidity is only a property of the collection of molecules. The mind-brain reductionist similarly argues that the mind’s properties—sensation, thinking, feeling, willing—are features of the brain, although individual molecules that make up the brain don’t have these properties.