I will explain this phenomenon and its conceptual framework further below, as well as its adaptation to an alchemical frame of reference, where I suggest it can be seen as a ‘shadow alchemical vas’, where shadow refers to ‘the sum of all the unpleasant qualities one wants to hide, the inferior, worthless and primitive side

of man’s nature’ (Samuels et al.,1986, p. 138). In alchemical language, the vas, or crucible, was the retort, the vessel in which the chosen substances were mixed together. The aim was to release what was good, new or precious from this mixing process. As ‘shadow vas’, the claustrum does the opposite – it traps real and potential ‘gold’ in a self-limiting container.