438 THOUGHTS ON THE 



OJ the common Division of Motion, that it is equally deficient 

 in point of Utility and of Discrimination. 



iv. 



The division of motion in the philosophy in vogue appears 

 to be superficial and without foundation, as it forms its 

 distribution of it only by its effects, and does not at all 

 conduce to our knowledge of it by its causes. For genera 

 tion, corruption, increase, diminution, alteration, removal 

 to place, are only the operations and effects of motions, 

 which having attained to the production of a visible trans 

 mutation of things, palpable to vulgar observation, are 

 (in the inertness of common apprehension) distinguished 

 by these appellations. We have no doubt that the mean 

 ing of the terms stands thus : that when bodies in the 

 progression of their motion (of whatever character the mo 

 tion be) have reached that point at which they assume a 

 new form, or lay aside the old, (forming a sort of full break, 

 and the completion of a regular stage of that motion), this 

 is termed the motion of generation and corruption. Again, 

 if the configuration remaining the same, they acquire only 

 a new quantity or measure of dimension, this is called the 

 motion of increase and diminution : so also, if the mass and 

 the outline of the object remain unaltered, yet its quality, 

 operations, and properties, undergo change, this is said to 

 be the motion of alteration ; lastly, if the body continue 

 unmodified in figure matter and quantity, but change its 

 place, and that only, this is indicated by the words motion 

 of removal. But to him who looks into this matter with 

 something more of penetration and accuracy, these phrases 

 will appear to represent only points in the measurement of 

 motion, pauses and breaks in it, or, as it were, the succes 

 sive courses motions have to run, and tasks they have to 

 perform, but to convey no real distinctions ; as they only 

 point to that which has been done, but scarcely even hint 

 at the mode of doing it. Words of this description are 

 required for the purpose of giving information, and adjusted 

 to the forms of the scholastic logic, but they are utterly 

 unproductive of physical knowledge. For they all signify 

 motions combined, recombined, and in manifold ways still 

 further combined ; whereas men of more acute meditation 

 ought to penetrate to simpler principles. For the prin 

 ciples, the sources, the causes, and the modes of motion, 

 that is, the tendencies and appetencies of every form of 

 matter, are the proper field of philosophy ; and so in their 



