354 INDUCTION. 



so far as it was known up to that time. A similar and still 

 greater step was made when these laws, which at first did not 

 seem to be included in any more general truths, were dis- 

 covered to be cases of the three laws of motion, as obtaining 

 among bodies which mutually tend towards one another with 

 a certain force, and have had a certain instantaneous impulse 

 originally impressed upon them. After this great discovery, 

 Kepler's three propositions, though still called laws, would 

 hardly, by any person accustomed to use language with pre- 

 cision, be termed laws of nature : that phrase would be reserved 

 for the simpler and more general laws into which Newton is 

 said to have resolved them. 



According to this language, every well-grounded inductive 

 generalization is either a law of nature, or a result of laws of 

 nature, capable, if those laws are known, of being predicted 

 from them. And the problem of Inductive Logic may be 

 summed up in two questions : how to ascertain the laws of 

 nature ; and how, after having ascertained them, to follow 

 them into their results. On the other hand, we must not 

 suffer ourselves to imagine that this mode of statement amounts 

 to a real analysis, or to anything but a mere verbal trans- 

 formation of the problem ; for the expression, Laws of Nature, 

 means nothing but the uniformities which exist among natural 

 phenomena (or, in other words, the results of induction), when 

 reduced to their simplest expression. It is, however, some- 

 thing to have advanced so far, as to see that the study of 

 nature is the study of laws, not a law ; of uniformities, in the 

 plural number : that the different natural phenomena have 

 their separate rules or modes of taking place, which, though 

 much intermixed and entangled with one another, may, to a 

 certain extent, be studied apart : that (to resume our former 

 metaphor) the regularity which exists in nature is a web com- 

 posed of distinct threads, and only to be understood by tracing 

 each of the threads separately ; for which purpose it is often 

 necessary to unravel some portion of the web, and exhibit the 

 fibres apart. The rules of experimental inquiry are the con- 

 trivances for unravelling the web. 



