"Association of Ideas" is arrangeable under two heads: the discoverable, and the undiscoverable. Of the last, first. How often do we every day jump from one point to another, as distinct in themselves as the sublime and the ridiculous, and far more widely asunder? We are talking of A, and Z starts up in the mind. White is the subject of the speculation, and in walks Black. It may be said, that as likes beget likes, so opposites beget opposites; and it may be very true that if you cannot directly call Z to mind when you want him, it is advisable to recollect A, as likelier to remind you of him than Y, or any other alphabetician. Granted; but, on the same principle, when you want to think of water, you should order in some brandy. The connexion may be close, although the elements are opposite. In like manner, we are told, when trying to recal some reprobate's _alias_, to think of a church of the same name; as we might think of a duellist, to suggest the image of a practical Christian. So, if we would be reminded of the truth and simplicity of Shakspeare, we ought to remember how his plays are sometimes acted; we shall see the high point from the low. Again, the image of a poor-box might be useful to help us to the idea of fulness; as that of a medicine-chest might be, to suggest the sense of turtle and venison. But we need not multiply opposites; grant that suggestions arise thus, when ideas stand opposed in straight lines--when the electric wire runs direct between them, wonderfully connecting the remote--yet how are we to account for the association of ideas in cross-roads, where there cannot possibly be the slightest connexion--where the fancy starts off at all sorts of angles, or wriggles through all kinds of crooked lines, without an apparent chance of stumbling upon the image that nevertheless comes uppermost? Cases constantly occur where there is not a particle of affinity. The child-idea is born without a parent-idea; there is not the shadow of a traceable relationship. We are discussing the merits of Cerito, and one of Euclid's problems bursts upon us; we are quietly repeating to ourselves some verses of the Odyssey, and suddenly the mind wanders to the subject of muffins. What connexion is there between shirt-frills and glass bottles? Yet how rapidly may one follow the other, like debtor and creditor, and become as intimately related as needle and thread!