450 BACON 



shivering of the head. This motion is visible also In other 

 cases. Thus it is observed in some kinds of antiperistasis, as 

 in the middle region of the air, the cold of which appears to be 

 occasioned by the rejection of cold from the regions of the 

 heavenly bodies ; and also in the heat and combustion observed 

 in subterranean spots, which appear to be owing to the rejec- 

 tion of heat from the centre of the earth. For heat and cold, 

 when in small quantities, mutually destroy each other, whilst 

 in larger quantities, like armies equally matched, they remove 

 and eject each other in open conflict. It is said, also, that cin- 

 namon and other perfumes retain their odor longer when placed 

 near privies and foul places, because they will not unite and 

 mix with stinks. It is well known that quicksilver, which 

 would otherwise reunite into a complete mass, is prevented 

 from so doing by man's spittle, pork lard, turpentine, and the 

 like, from the little affinity of its parts with those substances, so 

 that when surrounded by them it draws itself back, and its 

 avoidance of these intervening obstacles is greater than its de- 

 sire of reuniting itself to its homogeneous parts ; which is what 

 they term the mortification of quicksilver. Again, the differ- 

 ence in weight of oil and water is not the only reason for their 

 refusing to mix, but it is also owing to the little affinity of the 

 two; for spirits of wine, which is lighter than oil, mixes very 

 well with water. A very remarkable instance of the motion in 

 question is seen in nitre, and crude bodies of a like nature, which 

 abhor flame, as may be observed in gunpowder, quicksilver, 

 and gold. The avoidance of one pole of the magnet by iron 

 is not (as Gilbert has well observed), strictly speaking, an avoid- 

 ance, but a conformity, or attraction to a more convenient situ- 

 ation. 



Let the eleventh motion be that of assimilation, or self-multi- 

 plication, or simple generation, by which latter term we do not 

 mean the simple generation of integral bodies, such as plants 

 or animals, but of homogeneous bodies. By this motion ho- 

 mogeneous bodies convert those which are allied to them, or 

 at least well disposed and prepared, into their own substance 

 and nature. Thus flame multiplies itself over vapors and oily 

 substances, and generates fresh flame ; the air over water and 

 watery substances multiplies itself and generates fresh air ; the 

 vegetable and animal spirit, over the thin particles of a watery 

 or oleaginous spirit contained in its food, multiplies itself and 

 generates fresh spirit ; the solid parts of plants and animals, as 

 the leaf, flower, the flesh, bone, and the like, each of them as- 

 similates some part of the juices contained in their food, and 

 generate a successive and daily substance. For let none rave 

 with Paracelsus, who (blinded by his distillations) would have 

 it, that nutrition takes place by mere separation, and that the 



