years, the learner may be led on from those perceptions which are involuntary, intuitive, and pleasurable, to the very highest points of abstruse speculation ; scarcely knowing when he has made an effort to rise :just as a traveller, in certain districts of central Asia, may pursue an easy road from the dead levels of the Caspian steppes, to the most elevated Tartarian table landsoverlooking a continent; and scarcely know that he has been holding an upward path.
Sameness and differencedifferences among things very nearly related; and samenesses connecting things very remote, are the objects of the physical sciences: and it is these same points of contrast, and of harmony, that supply the best incitements to the opening intellectual powers. When, to some considerable extent, the sentient and organized families have been brought forward, first, as to their external resemblances of form; next, as to their habits; and lastly, as to the laws of their internal structure, and vital functions, then comes the time for ascending to another stage, and for advancing towards those principles which involve IDENTITY OF LAW, rather than analogy of principle. This more advanced species of mental culture is afforded by those of the physical sciences that are more or less dependent upon mathematical reasoning. It is therefore now assumed that a moderate proficiency in the mathematics, has been made by the learner. Although strictly speaking, it is not analogy, but identity of principle, that connects the falling of a stone, or its tangential leap from a sling, with the motions of the planetary system, nevertheless, the two classes of facts being immensely remote from each other, as observed by the human eye, and the one being familiar, while the other is shrouded in a sort of mystery, the effect upon the young mind, made by adducing the one, in illustration of the other, is nearly the same as in any instance of a mere analogy; and these
