NOVUM ORGANUM 445 



merits of this motion, are heat and cold. For instance, the 

 air, if expanded by tension (as by suction in the glass egg), 

 struggles anxiously to restore itself; but if heat be applied, it 

 strives, on the contrary, to dilate itself, and longs for a larger 

 volume, regularly passing and migrating into it, as into a new 

 form (as it is termed) ; nor after a certain degree of expansion 

 is it anxious to return, unless it be invited to do so by the 

 application of cold, which is not indeed a return, but a fresh 

 change. So also water, when confined by compression, resists, 

 and wishes to become as it was before, namely, more expanded ; 

 but if there happen an intense and continued cold, it changes 

 itself readily, and of its own accord, into the condensed state of 

 ice ; and if the cold be long continued, without any intervening 

 warmth (as in grottoes and deep caves), it is changed into crys- 

 tal or similar matter, and never resumes its form. 



Let the fifth be that which we term the motion of continuity. 

 We do not understand by this simple and primary continuity 

 with any other body (for that is the motion of connection), but 

 the continuity of a particular body in itself; for it is most 

 certain that all bodies abhor a solution of continuity, some more 

 and some less, but all partially. In hard bodies (such as steel 

 and glass) the resistance to an interruption of continuity is 

 most powerful and efficacious, whilst although in liquids it ap- 

 pears to be faint and languid, yet it is not altogether null, but 

 exists in the lowest degree, and shows itself in many experi- 

 ments, such as bubbles, the round form of drops, the thin threads 

 which drip from roofs, the cohesion of glutinous substances, 

 and the like. It is most conspicuous, however, if an attempt 

 be made to push this separation to still smaller particles. Thus, 

 in mortars, the pestle produces no effect after a certain degree of 

 contusion, water does not penetrate small fissures, and the air 

 itself, notwithstanding its subtilty, does not penetrate the pores 

 of solid vessels at once, but only by long-continued insinuation. 



Let the sixth be that which we term the motion of acquisition, 

 or the motion of need. It is that by which bodies placed 

 amongst others of a heterogeneous and, as it were, hostile 

 nature, if they meet with the means or opportunity of avoiding 

 them, and uniting themselves with others of a more analogous 

 nature, even when these latter are not closely allied to them, 

 immediately seize and, as it were, select them, and appear to 

 consider it as something acquired (whence we derive the name), 

 and to have need of these latter bodies. For instance, gold, or 

 any other metal in leaf, does not like the neighborhood of air ; 

 if, therefore, they meet with any tangible and thick substance 

 (such as the finger, paper, or the like), they immediately adhere 

 . and are not easily torn from it. Paper, too, and cloth, and 

 the like, do not agree with the air, which is inherent and mixed 



