consist:--and to prove that animals being unable to substitute a term for their perceptions, are incapable of the process which we denominate thought or reflection. To fathom this mystery, is perhaps impossible; but, from attentively watching that which passeth within us,--from considering the state of animals which want this endowment altogether, it seems to be a law of our intellectual constitution, that our thoughts or reflections can only consist of the terms which represent our perceptions; and this is more evidently true, when we reflect on those subjects which are of a general or abstract nature. Whoever will attentively watch the operation of his own mind,--for this subject admits of direct experiment,--will find that he employs terms when he conducts the process of reflection. In order to afford a fair trial, it is necessary that he should be alone, and subject to no interruptions. It will also add to the facility of the experiment, that he select a subject with which he is but little acquainted, as the process will be more deliberate. On topics with which we are familiar, we have acquired a rapidity of exercise which renders the detection of the process more difficult and perplexing. In this trial, he will be aware that he is repeating words as the materials of his thoughts. If the subject on which he should think involves persons with whom he is acquainted, or scenes he has viewed, he will, in addition to the terms he employs, have the pictures, or visible phantasmata, of these presented to his mind, conjunctively with such words. That we actually employ terms in this process is evident in many, who, when exercising their thoughts on any subject, are found, as we term it, talking to themselves; so that we are enabled to observe the motion of their lips: and this circumstance is to be noticed in most persons when they are counting. The contrivances of language enable us to connect our thoughts; for our perceptions are distinct and individual, and of themselves can possess no elective attraction to _associate_ and combine: they may however, by repetition or habit, become so allied, that the occurrence of one will excite the sequence of the other. We ordinarily recollect them very much in the order and succession of their occurrence; but we are also able to arrange and class them, and by such means, of recollecting them according to the artificial order of their distribution. This may be exemplified in the various expedients that have been devised for the acquirement and retention of knowledge: thus, chronology records events according to the order of their occurrence; an encyclopaedia arranges according to alphabet or subject; and the most perfect of this kind, like the index to a book, consists in their mutual reference.