6. We find in our mind often an association of ideas which is accidental and arbitrary in its origin, but once being established is almost inseparable and imperative. This wrong association “has such an influence, and is of so great force to set us awry in our action, as well moral as natural, passions, reasonings, and notions themselves, that perhaps there is not any one thing that deserves more to be looked after” (9: vol. ii, Book II, chapter 33, § 9). To prevent such erroneous associations in the mind of children, the strict order of learning should be observed. “Give them first one simple idea, and see that they take it right, and perfectly comprehend it, before you go any further; and then add some other simple idea which lies next in your way to what you aim at; and so proceeding by gentle and insensible steps, children without confusion and amazement will have their understandings opened and their thoughts extended farther than could have been expected” (7: p. 158). * * * * * Mathematics is recommended as a help to the training of reasoning power, for a mathematical demonstration represents the coherent process of reasoning. As for logic, he thinks with Bacon that it, “catching at what it cannot reach, has served to confirm and establish errors, rather than to open a way to truth” (8: p. 19). No general improvement of memory is affected by any usual method of “committing to memory,” or “learning by heart.” For in his psychology (9: vol. ii, Book II, chapter xxxiii, xxxix; vol. i, Book II, chapter x) our memory of ideas or impressions depends upon the strength of power to hold them in mind--namely, attention, on the one hand, and upon that of the power to retain and recall them, on the other. Yet the intensity and duration of attention is largely determined by interest, and the retentive power is owing to our constitution, and therefore beyond education. Thus he says: “What the mind is intent upon and careful of, that it remembers best, ... to which if method and order be joined, all is done, I think, that can be for the help of a weak memory; and he that will take any other way to do it, especially that of charging it with a train of other people’s words, which he that learns cares not for, will, I guess, scarce find the profit answer half the time and pains employed in it.” For memory is not a power that is transferable from one thing to another. “The learning pages of _Latin_ by heart, no more fits the memory for retention of anything else, than the graving of one sentence in lead makes it the more capable of retaining firmly any other characters” (7: pp. 154-155). Improvement of memory can come only through the formation of habits of fixating attention and of orderly association. Thus, to sum up, learning by self-active, pleasurable exercise of mental powers, directed in an orderly manner and constantly repeated, is the fundamental principle of intellectual education.