The presence of ideas and thoughts in our consciousness is as strictly subordinated to the principle of sufficient reason in its different forms as the movement of bodies to the law of causality. It is just as little possible that a thought can appear in the mind without an occasion as that a body can be set in motion without a cause. Now this occasion is either _external_, thus an impression of the senses, or _internal_, thus itself also a thought which introduces another thought by means of _association_. This again depends either upon a relation of reason and consequent between the two; or upon similarity, even mere analogy; or lastly upon the circumstance that they were both first apprehended at the same time, which again may have its ground in the proximity in space of their objects. The last two cases are denoted by the word _à propos_. The predominance of one of these three bonds of association of thoughts over the others is characteristic of the intellectual worth of the man. The first named will predominate in thoughtful and profound minds, the second in witty, ingenious, and poetical minds, and the third in minds of limited capacity. Not less characteristic is the degree of facility with which one thought recalls others that stand in any kind of relation to it: this constitutes the activeness of the mind. But the impossibility of the appearance of a thought without its sufficient occasion, even when there is the strongest desire to call it up, is proved by all the cases in which we weary ourselves in vain to _recollect_ something, and go through the whole store of our thoughts in order to find any one that may be associated with the one we seek; if we find the former, the latter is also found. Whoever wishes to call up something in his memory first seeks for a thread with which it is connected by the association of thoughts. Upon this depends mnemonics: it aims at providing us with easily found occasioners or causes for all the conceptions, thoughts, or words which are to be preserved. But the worst of it is that these occasioners themselves have first to be recalled, and this again requires an occasioner. How much the occasion accomplishes in memory may be shown in this way. If we have read in a book of anecdotes say fifty anecdotes, and then have laid it aside, immediately afterwards we will sometimes be unable to recollect a single one of them. But if the occasion comes, or if a thought occurs to us which has any analogy with one of those anecdotes, it immediately comes back to us; and so with the whole fifty as opportunity offers. The same thing holds good of all that we read. Our immediate remembrance of words, that is, our remembrance of them without the assistance of mnemonic contrivances, and with it our whole faculty of speech, ultimately depends upon the direct association of thoughts. For the learning of language consists in this, that once for all we so connect a conception with a word that this word