6 ideas
When thinking alone fails to solve a problem, talk it through with anyone nearby. The point is not that they will tell you the answer but that you will tell it to yourself. The idea is not fully formed before speech; it comes into being as you speak ('l'idée vient en parlant').
Starting a sentence with only a vague beginning commits the mind to finishing it, and that obligation drives the half-formed thought toward clarity. Speakers buy the time this needs with drawn-out conjunctions, filler phrases, and needless appositions, stalling while the idea finishes forming.
On 23 June 1789 the king's master of ceremonies ordered the Third Estate to disperse. Mirabeau began with a neutral 'Yes, we have heard the king's command,' apparently without knowing where he was headed. Sentence by sentence he escalated until he declared they sat by the will of the people and would leave only at bayonet point, a revolutionary stance produced in the act of replying.
A listener is not a passive receiver but a source of pressure. Their expression, their visible wish to interrupt, and the sense that they are following all push the speaker's mind to work harder. Kleist likens this to an uncharged body brought near an electrically charged one, which becomes charged without any contact.
'It is not we who know, but first of all a certain condition of ours which knows.' Understanding is not a fixed stock we carry around and draw on at will. It appears when the mind is put in a particular aroused, engaged condition, which is why the same person can be brilliant in one setting and blank in another.
Public examinations put abrupt questions to a candidate whose mind has not yet been set in motion. This produces blankness in capable people and rewards those who recite stored answers. A fairer examiner would draw thought out gradually, supplying the conditions in which it is actually produced, rather than demanding finished answers on command.