Varieties and valences of unsayability

Examples of unsayability of the most disparate sorts are cited from literature (Shakespeare, Melville, James, Aeschylus, and others) in order to suggest the uncircumscribable diversity of motives for unsayability. The question is whether they all have anything in common. When something cannot be said because of politeness or obscenity or deceit or strategy, does this have anything to do with the metaphysical motives for unsayability? These things are not per se unsayable but only conditionally so, under certain circumstances. The problem is that any way of distinguishing accidental from essential unsayability is itself circumstantial. Any essential unsayability must necessarily remain, precisely, unsayable. Therefore any determinate distinction between essential and contingent unsayability itself proves to be inarticulable. Questioned in this way as to its final purport and significance, all discourse, in effect, falls under the sway of what cannot be said.