It took a creative genius on the level of Carl Jung to discover, in the ancient art of alchemy, an instructive metaphor for psychotherapy: to assert that the healing soul, like the basic starting materials of the alchemical technique, is transformed by a process no less noble and mystical than the one that searched for gold and elixirs of immortality.
If we wanted to update this metaphor for a modern audience, substituting chemistry for alchemy, it would serve us well to choose the technique of column chromatography, which is used by chemists to purify compounds from a given solution.
Let’s follow this metaphor and see where it takes us — and see whether we can, like the process itself, extract some useful material from it.
The basic setup is as follows. A compound of interest is already dissolved, as one of many, in a solution. The solution is then poured through the top of a vertical column. Down it travels through the column until, reaching the other side, it accumulates into a collecting flask.
It would only be a matter of moving the solution from one place to another, if it wasn’t for the fact that the column contains a substance, the ‘stationary phase’, that catches certain dissolved compounds, while letting others flow through it.
This catching can occur in a variety of ways. The stationary phase may contain pores, which bind to only the smaller compounds. Or it may contain charged ions, which bind to compounds of the opposite charge. More meticulous separations can be accomplished by the preparation of antibodies, which bind only to specific proteins.
In some cases, the compound of interest is what elutes through to the collecting flask. Otherwise, it is retrieved from the stationary phase by an additional eluting step. Either way, what has been accomplished is the separation of the compound of interest from a solution containing many others: a purification process, an extraction.