On the other hand, the chemical changes which follow a body’s acquisition of heat, setting in the moment that heat has reached its acme and starts to decline, are as universal as the universe itself. They are conditioned, it is true, by the body’s size and by the position that body occupied in the primal nebula, but they depend directly upon the degree of heat the body had attained. The larger the planet, the higher the temperature it reached and the fuller its possibilities. Even the planets are born to their estate. Thus the little meteorites live their whole waking life during the few seconds they spend rushing through our air. For then only does change affect their otherwise eternally inert careers. That the time is too short for any important experience is evident on their faces. Heat is most intimately associated with the very constitution of matter. It is, in fact, merely the motion of its ultimate particles, and plays an essential part in their chemical relations. Just as a certain discreet fervor and sufficient exposure for attraction to take, make for matrimony, so with the little molecules, a suitable degree of warmth and a propitious opportunity similarly conduce to conjunction; too fiery a temperament resulting in a vagabondage preventative of settled partnership and too cold a one in permanent celibacy. You may think the simile a touch too anthropomorphic, but it is a most sober statement of fact. Indeed, it is more than probable that in some dull sense they feel the impulse, though not the need of expressing it in verse. That metals can remember their past states seems to have been demonstrated by Bose, and is certainly in keeping with general principles as we know them to-day. For memory is the partial retention of past changes, rendering those changes more facile of repetition. A high degree of heat, then, makes chemical union impossible, because the great speeds at which the molecules are rushing past each other prevents any of them being caught. Lack of speed is equally deterrent. Nor is it wholly or even principally, perhaps, a movement of the whole which is here concerned, but a partitive throbbing of the molecule itself. Certain it is that great cold is as prohibitive of chemic combination as great heat. Phosphorus, which evinces such avidity for oxygen at ordinary temperatures as to have got its name from the way it publishes the fact, at very low ones shows a coolness for its affinity amounting to absolute unconcern. Thus only within a certain range of temperature does chemical combination occur. To remain above or below this is to stay forever immortally dead. To get hot enough in the first place, and then subsequently to cool, are therefore essential processes to a body which is to know evolutionary advance.