the quality in question is recognized as belonging to something quite familiar, and yet not often thought of, in that point of view, there is excited precisely the sort of agreeable surprise of which good use may be made in awakening the intellect. That the atmosphere is transparent, a child readily grants; but he starts at first hearing the invisible, impalpable air he breathes associated with lead, or with stones.
Or thusWhat substances, which are solid when deprived of heat, do we usually find in a fluid state? Water, yes, andquicksilver. A wooden hoop, thrown aloft, re-bounds several feet from the earth: it is, elastic. But this distended bladder does so too; is bladder elastic? no; but that with which it is filled with is so, namelyair: a hoop, and a steel spring, andthe atmosphere, are then alike in this respect, they are allelastic. The atmosphere therefore isheavy, like lead; transparent, like water; and elastic, like steel. Or again: Some bodies are permanently of one colour; gold is yellow, silver white, a rose-leaf red, an iris blue; but other bodies exhibit changing colours, when seen in different positions; and seem in themselves to be colourless: what are the instances?mother of pearl, drops of rain, or dew, garden cobwebs, soap bubbles, films of oil upon water, and many kinds of crystals.
The sense of RELATION is, in strictness, only the discernment of a sameness, under circumstances of difference; as when a part is seen to be a third, or a fourth, of the whole; the part is thought of as many times over as will make it equal to, or the same as, the whole. The relation of sequence constitutes the principal ground or material of that ulterior and important process of education which bears upon Cause and Effect. And the relation of proportion also, is too intimately connected with mathematical principles, to be easily treated of in this stage of our
