- Obscurity, speaking in fables, non-clarity, indirectness. Multiple layers to one's teaching. This possibly for the sake of pedagogy.
- Teachings for the public versus teachings for the initiates/elite/true disciples. Two contradictory or opposed layers to one's teaching.
The former and the latter are quite different, and I wonder whether the latter might be far less common than the former.
It seems clear that some thinkers, particularly in ancient Greece and Rome, had opposed esoteric and exoteric aspects to their work, and that we should acknowledge and try to discern this where it exists.
But I'd question whether esotericism is "of the greatest importance for our understanding of the whole course of Western philosophy". The author seems to think of it almost as a kind of skeleton key, as though maybe there is a significant stream of thought that people have radically misunderstood. The idea of a hidden thread of elite, secret knowledge has an alluring, conspiratorial feel to it that the author doesn't mention -- a vibe that is not so foreign to our modern sensibilities (Scientology, Kabbalah, New Age, ...).
Melzer writes that "with pedagogical esotericism, the writer actually embraces concealment and obscurity (of the right kind) as a positive good and as something essential to the primary purpose of his act of writing: philosophical education". How does this not describe art of all kinds -- e.g. fiction writing -- where the creator has a didactic purpose, but artfully weaves this into their work? ("Ars est celare artem.") Again, there is no distinction made between nonclarity and the demand for active, engaged, creative reading and thinking on the one hand, and on the other, radically opposed esoteric and exoteric meanings.
> It follows, then, that a writer who seeks to educate philosophically through Socratic dialectics must make a special effort to enter sympathetically into the received opinions of his time and place—though he may consider them false—while pointing quietly to certain puzzles or contradictions within those opinions.
"For this reason I have no doubt that if you deign to take the trouble in the first place of correcting this work (for being conscious not only of my infirmity, but also of my ignorance, I should not dare to state that it was free from errors), and then, after adding to it these things that are lacking to it, completing those which are imperfect, and yourselves taking the trouble to give a more ample explanation of those things which have need of it, or at least making me aware of the defects so that I may apply myself to remedy them; when this is done and when finally the reasonings by which I prove that there is a God, and that the human soul differs from the body, shall be carried to that point of perspicuity to which I am sure they can be carried in order that they may be esteemed as perfectly exact demonstrations, if you deign to authorize your approbation and to render public testimony to their truth and certainty, I do not doubt, I say, that henceforward all the errors and false opinions which have ever existed regarding these two questions will soon be effaced from the minds of men."
That's one sentence! The translation is from The Philosophical Works of Descartes, which was apparently translated from French, which was translated from Latin. So there could be some cause for this style in the translation work.
Or, should I say that my self-generated perception after a compressed review of the literature has left me inclined to believe that the author is highly self-aware and wry, with their oral muscular hydrostat firmly implanted in either the left or right side of the orifice.