Modern philosophy focuses on the mind's universal features, such as qualia and intentionality, typically with the aim of reducing them to physical processes. This endeavour runs into so-called "hard problems", much like the alchemists' pursuits in ages past. Meanwhile, the mind's particularity – its deepest, most distinctive, defining characteristic – is surprisingly overlooked. Each mind is a particular, in a quintessential sense: I experience life through my own, private, unique, and non-duplicable perspective, which is what fundamentally distinguishes me from the (...) rest of the universe and gives me my unique identity. Out of billions of human bodies, it was the formation of what I call "my" body that led to me coming into existence. Why? There seems to be nothing inherently special about this body compared to the billions of others, and I can easily imagine it belonging to another mind and me experiencing life through another body or not existing at all. While for an inanimate particular, such as a chair, it is nonsensical to ask why, when it was constructed, it was that chair and not some other one that came into existence, for a conscious being the question "Why was it I that was brought into existence" is of the utmost relevance and should concern anyone that takes their existence seriously and marvels at its mystery. In this paper it is argued that the particularity of a mind can not be explained or deduced through any supposed composition of that mind, or even in terms of any external factors. Organisation of the brain's matter, architecture of neural circuitry, genetic sequence, combination of parents, or even hypothetical immaterial constituents as posited by panpsychism, cannot tell us anything about the particularity of the mind that possesses them. To begin with, all such combinations of constituents are duplicable (e.g. two or more minds could, theoretically, have identical bodies), or the constituents are exchangeable between minds (the matter constituting the body of one mind could, theoretically, be gradually exchanged with the matter of another mind's body), whereas the particularities of minds are not. Furthermore, the complete symmetry among the particularities of all minds implies that no combination of supposed constituents can have any a priori special relation to any particular mind; all such combinations are equally (a priori) neutral towards all particularities, lacking anything that could serve as a basis for pointing to a specific emergent mind, e.g.\ you rather than me. Finally, the particularity of a mind is something completely private to that mind itself and can be found nowhere else in the universe. The conclusion is that the mind/person/self is a simple (i.e. non-composite) entity, a simple substance, as Descartes proposed. (shrink)