We must now turn to the question of why it was that Adam should have been selected as a symbol for the prima materia or transformative substance. This was probably due, in the first place, to the fact that he was made out of clay, the "ubiquitous" materia vilis that was axiomatically regarded as the prima materia and for that very reason was so tantalizingly difficult to find, although it was "before all eyes." It was a piece of the original chaos, of the massa confusa, not yet differentiated but capable of differentiation; something, therefore, like shapeless, embryonic tissue. Everything could be made out of it.
— Carl Gustav Jung
Clay was everywhere — that is the point, and the trap. The prima materia is not hidden in some remote chamber of the psyche requiring initiation to unlock; it is the undifferentiated stuff already underfoot, the mass confusion already present before anyone thought to name it. Jung reads the alchemists' choice of Adam precisely this way: the first man is not selected because he is noble or luminous but because he was fashioned from dirt, from the most commonplace and overlooked of substances. The very ubiquity of the materia vilis is what makes it invisible. We walk past it daily looking for something more distinguished.
What this passage discloses is how the psyche refuses its own raw material. The massa confusa — shapeless, embryonic, not yet differentiated — is genuinely uncomfortable to inhabit. It has no form that can be held onto, no narrative that already resolves it. The alchemists knew this, which is why they kept insisting the work begins where you are standing, not where you would prefer to stand. Differentiation is not imposed on something foreign; it is drawn out of what was always there, waiting for no more exotic a condition than your willingness to stop looking past it.
Carl Gustav Jung·Mysterium Coniunctionis: An Inquiry into the Separation and Synthesis of Psychic Opposites in Alchemy·1955