Montaigne: "By one kind of barking of a dogge, the horse knoweth he is angrie; by another voice of his, he is nothing dismaid. Even in beasts that have no voice at all, by the reciprocall kindnesse which we see in them, we easily inferre there is some other meane of entercommunication: their jestures treat, and their motions discourse.
And why not, as well as our dumbe men dispute, argue, and tell histories by signs? I have seene some so ready and so excellent in it, that (in good sooth) they wanted nothing to have their meaning perfectly understood.
What doe we with our hands? Doe we not sue and entreat, promise and performe, call men unto us and discharge them, bid them farewell and be gone, threaten, pray, beseech, deny, refuse, demand, admire, number, confesse, repent, feare, bee ashamed, doubt, instruct, command, incite, encourage, sweare, witnesse, accuse, condemne, absolve, injurie, despise, defie, despight, flatter, applaud, blesse, humble, mocke, reconcile, recommend, exalt, shew gladnesse, rejoyce, complaine, waile, sorrow, discomfort, dispaire, cry out, forbid, declare silence and astonishment: and what not? with so great variation and amplifying as if they would contend with the tongue.
And with our head doe we not invite and call to us, discharge and send away, avow, disavow, belie, welcome, honour, worship, disdaine, demand, direct, rejoyce, affirme, deny, complaine, cherish, blandish, chide, yeeld, submit, brag, boast, threaten, exhort, warrant, assure, and enquire? What doe we with our eye-lids? and with our shoulders? To conclude, there is no motion nor jesture that doth not speake, and speakes in a language very easie, and without any teaching to be understood: nay, which is more, it is a language common and publike to all: whereby it followeth (seeing the varietie and severall use it hath from others) that this must rather be deemed the proper and peculiar speech of human nature."
It's uncomfortably easy to think of Knowledge as something for Laying Up (like virtue in heaven) or Down (like claret in cellars) or By (like sovereigns in socks): got methodically, piecemeal, cumulatively; the best hedge against inflation. Even if forgotten, our merit in having known it once will endure as long as diploma-parchment. For knowledge-merit reflects not the facts we know but the fact that we knew them, once. This is true, one might say, almost by definition. For how can there be merit without acknowledgement? acknowledgement without reward? or reward without a guarantee against devaluation?
The melancholy part is not that knowledge decays, rather that it decays faster than we do ourselves; but that, after all, is the situation melancholy was invented to cope with. More alarming is the realization that knowledge-talk can take on a life of its own. Of man and idea, which then possesses the other?
Knowing is indefinitely corrigible; and only this gives hope. `L'enfant dit avant de savoir ce qu'il dit' (Alain); and the adult also. `We learn the current mass of words, and they rest in our heads without activity and without use; only bit by bit through experience, do we first come to know what a treasure we have and to think something with the words' (Hegel). For some, the game is even more fun if the input from experience is dispensed with.
Answerer must diagnose, in questioner, not his knowledge or his ignorance but his knowledge-ignorance, expressible in units of the form `knows r but (hard though this is to believe) is ignorant of p' -- krip for short. Many more krips are commonly attested than teachers allow for. This is the area where Homo sapiens shows most variety, and which places the greatest demand on the teacher's imagination, or charity.