NOVUM ORGANUM. 189 



parts with those substances, so that when surrounded by 

 them it draws itself back, and its avoidance of these inter 

 vening obstacles is greater than its desire of reuniting itself 

 to its homogeneous parts; which is what they term the 

 mortification of quicksilver. Again, the difference 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 are lighter than oil, mix 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 avoidance, but a conformity, or attraction to 

 a more convenient situation. 



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

 multiplication, 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 homogeneous bodies convert those which 

 are allied to them, or at least well disposed and prepared, 

 into their own substance and nature. Thus flame multi 

 plies itself over vapours 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 oleagi 

 nous spirit contained in its food, multiplies itself and gene 

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

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

 assimilate 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 eye, nose, brain, and liver lie concealed in 

 bread and meat, the root, leaf, and flower in the juice of 

 the earth; asserting that just as the artist brings out a 

 leaf, flower, eye, nose, hand, foot, and the like, from a rude 

 mass of stone or wood by the separation and rejection of 

 what is superfluous ; so the great artist within us brings 

 out our several limbs and parts by separation and rejection. 

 But to leave such trifling, it is most certain that all the 

 parts of vegetables and animals, as well the homogeneous 

 as organic, first of all attract those juices contained in their 

 food, which are nearly common, or at least not very dif 

 ferent, and then assimilate and convert them into their own 



