Without a proper vessel, none of the processes of of alchemy can be accomplished. There must be a container in order to differentiate the various substances from the massa confusa, of which Thomas Moore writes, "It takes a special frame of mind, a particular archetypal viewpoint...to enter the alchemical massa confusa..." The unconscious is this chaos, the prima materia of the Great Work. The need for a vessel begins the alchemical stage called separatio.
The alchemical vessel is a space that performs the function of transformation. It is both an imaginal space and a physical space. What is in the earth composes the animaterial vessel, whether it be glass, metal, stone, or body. As there can be no light without darkness, so there can be no conjunction without separation. The separated substance has form, even though it may be the same substance.
When we internalize the crucible in our souls we picture a vessel within our being which is open, allowing impurities or unwanted facets of the work to pass out or to dissipate away, as well as substances and forces to enter in from the universal spiritual. In this sense the crucible in our souls is a chalice, the lower part of which contains and holds a substance or constellation of forces while its upper part is open to universal spiritual influences. Unwanted energies can be allowed to safely flow out of our crucible and dissolve in the universal flow, and in the other direction energies can be gathered from the spiritual and allowed to descend to the bottom of our interior vessel (McLean).Keep in mind as we progress that to the alchemist, the Four Elements, air, water, earth, and fire, are vastly important. In this case, air contributes to the Great Work as spirit. As the Emerald Tablet says, "the wind nourished it [Truth] in her belly" (From the translation by Jabir ibn Hayyan, brackets mine).
One should not assume that the alchemical processes on a symbolic level pertain only to the interiority of a person. This "belly" can be the interiority of many things. The interiority of a garden, for example, most definitely exhibits alchemical processes that bring forth the fruit of the earth. Another good example is how the beauty of mountains are formed over millions of years of underground tectonic shifts. This is alchemy, as well, on a macroscopic scale. As above, so below.
The second type of vessel that McLean discusses is the retort. The retort is a sealed container, such as a glass flask. Glass is made from earth and fire. It must be made thick and strong to prevent the inner processes from shattering it. It is transparent so that the alchemist can view the opus. James Hillman calls glass "the material of distancing" (Hillman 592) because it separates the observed from the observer.
McLean likens the retort to "a womb or matrix in which the process of gestation or new birth arising out of primal components, can safely take place in us." The retort is said to be "hermetically sealed," an homage to Hermes, the guide of souls to the Underworld and patron and teacher of alchemy. The energies are sealed away so as to provide a state of isolation from outside influences. This place of isolation within the retort is an imaginal space where the naturals laws of the universe can be carried out unimpeded. The qualities of the glass retort can be compared to the psyche:
The psyche too is invisible; we grasp it only in reflection or we identify it with its contents – this dream, that feeling or memory. Psyche appears to be only what it contains. Glass, like psyche, is the medium by which we see into, see through. Glass: the physical embodiment of insight. The illusion of glass makes content and container seem to be the same, and because we see the content before we recognize that it is held by glass, we do not at first see its shape, its density, its flaws since our focus is fixed on the contents. Glass as subtle body requires a subtlety of noticing. The sophistication of the material needs sophistication of insight (Hillman 608).Finally, the third type of alchemical vessel is the still. We are most familiar with the still through its use in the distilling of alcoholic beverages, such as gin and whiskey. The use of stills can be traced back to Greek alchemists of the first century C.E. in Alexandria. Basically, the distillation process consists of separating mixtures by boiling. For instance, in the distilling of water, impurities are removed so that the final product can be used for medical uses, or where pure water is a necessity. It is not a chemical reaction, but a physical process of separation. This is yet another method used in the separatio. There are qualities within us and within the earth that must be wrested free from impurities in order to bring forth the hidden creative potential in us. I leave you with this passage from Dr. Nanci Shandera:
Distillation brings the creative out of us. It encourages all that we are to manifest in balanced and serenely powerful ways. It heralds the entry of the influence of the higher forces and the balancing of those forces with the lower ones, which provide our "groundedness," so crucial to wholeness.
Hillman, James. Uniform Edition of the Writings of James Hillman.Volume 5: Alchemical Psychology, Kindle edition. Dallas: Spring, 2013.
Moore, Thomas. The Garbage of our Lives. 10 Jan. 2013.
Shandera, Nanci. The Alchemy in Spiritual Progress: Part 7 Distillation. Alchemy Journal, Vol. 3, No. 1. Jan./Feb. 2002.