_B._ At the breaking up of a deer I have seen it plainly in his bowels as long as they were warm. And it is called the peristaltic motion, and in the heart of a beast newly taken out of his body; and this motion is called systole and diastole. But they are both of them this compounded motion, whereof the former causeth the food to wind up and down through the guts, and the latter makes the circulation of the blood. _A._ What kind of motion is the cause of cold? Methinks it should be contrary to that which causeth heat. _B._ So it is in some respect. For seeing the motion that begets heat, tendeth to the separation of the parts of the body whereon it acteth, it stands with reason, that the motion which maketh cold, should be such as sets them closer together. But contrary motions are, to speak properly, when upon two ends of a line two bodies move towards each other, the effect whereof is to make them meet. But each of them, as to this question, is the same. _A._ Do you think (as many philosophers have held and now hold), that cold is nothing but a privation of heat? _B._ No. Have you never heard the fable of the satyr that dwelling with a husbandman, and seeing him blow his fingers to warm them, and his pottage to cool it, was so scandalized, that he ran from him, saying he would no longer dwell with one that could blow both hot and cold with one breath? Yet the cause is evident enough. For the air which had gotten a calefactive power from his vital parts, was from his mouth and throat gently diffused on his fingers, and retained still that power. But to cool his pottage he straightened the passage at his lips, which extinguished the calefactive motion. _A._ Do you think wind the general cause of cold? If that were true, in the greatest winds we should have the greatest frosts. _B._ I mean not any of those uncertain winds which, I said, were made by the clouds, but such as a body moved in the air makes to and against itself; (for it is all one motion of the air whether it be carried against the body, or the body against it); such a wind as is constant, if no other be stirring, from east to west; and made by the earth turning daily upon its own centre; which is so swift, as, except it be kept off by some hill, to kill a man, as by experience hath been found by those who have passed over great mountains, and specially over the Andes which are opposed to the east. And such is the wind which the earth maketh in the air by her annual motion, which is so swift, as that, by the calculation of astronomers, to go sixty miles in a minute of an hour. And therefore this must be the motion which makes it so cold about the poles of the ecliptic. _A._ Does not the earth make the wind as great in one part of the ecliptic as in another? _B._ Yes. But when the sun is in Cancer, it tempers the cold, and still less and less, but least of all in the winter-solstice, where his beams are most oblique to the superficies of the earth.