With meaningful material, interference may arise in other ways. Take the alphabet again; _a_ is connected with _b_ through the frequent repetition of _abc_, but is also connected with _z_ by the phrase ‘_a_ to _z_.’ If, then, _a_ appears; and if the _b_-tendency and the _z_-tendency are of approximately equal strength; then there may be no connection at all; the two tendencies cancel or inhibit each other. A question may leave you dumb, not because you have no answer, but because you have so many different answers that no one of them can force through to expression. This sort of interference, which comes at the end of the associative process, is called =terminal inhibition=; there is another kind, coming at the beginning of the process, which we may call =initial inhibition=. If _a_ is already connected with _b_, then it is difficult to connect it with _k_; _b_ gets in the way. You have some particular fault of style, or you have fallen into the habit of spelling wrongly some particular word; you want to correct the fault, to spell aright. But every time that you are off guard, the mistake recurs; the existing connection _a-b_ heads off the desired connection _a-k_. Fortunately, there are compensations. If a group of tendencies, for instance, does escape interference, then _the brain settles down of itself_. Schoolboys, with a keen sense for economy of effort, learn their lessons only partway overnight, and find that a hasty review next morning is enough to fix them; the associative tendencies work while their owners sleep. The practised speaker, knowing that he has to talk on a certain subject at a certain date, marshals his present ideas in half-an-hour of concentrated attention, and then drops the whole thing; his brain incubates it for him; and when the appointed day comes near, he finds that his associative tendencies have practically prepared his address. Besides, the tendencies may converge, as well as interfere; we have seen how continued attention opens the mind to relevant facts and closes it against the irrelevant (p. 98). If they did not, it would be impossible for us to follow the thread of a paragraph, to say nothing of a chapter or of a whole book. =Convergence= thus offsets interference. We shall meet it in various forms later (§§ 42, 45, 65); meantime we leave the brain, and pass to the mental processes themselves. How are they connected?