Biologists use the term “expiation” to refer to the appropriation of an organ or structure that was designed for one function to serve a new function. Suppose that reading is an expiation of symbolic consciousness.
We know what it is to read: we see signs and read meaning. We complete our sight with insight. Put another way, we employ that data of our outer senses as a sort of map by which we navigate over the territory of our inner sense to the place where understanding may be had. By “symbolic consciousness” I refer to the ability to grasp types from their instances. It is something like the inverse of deduction, which proceeds from universal to particular. It is similar, but not identical to induction because intellection of a symbol is not achieved through abstraction but through intuition, or insight.
The signs-letters-words-tokens, etc. could be characterised as instructions for the configuration of consciousness or understanding such that what is written makes sense and becomes intelligible. Similarly, symbolism can be seen as an “instruction” or “map” that guides our consciousness to the table of communion, where we may partake of the substance (substantia, “under + standing”) or archetype or logos (λόγος) of that symbol.