ETHOLOGY. 



563 



empirical law derives whatever truth 

 it has from the causal laws of which 

 it is a consequence. If we know 

 those laws, we know what are the 

 limits to the derivative law ; while, 

 if we have not yet accounted for the 

 empirical law — if it rests only on 

 observation — there is no safety in 

 applying it far beyond the limits of 

 time, place, and circumstance in which 

 the observations were made. 



The really scientific truths, then, 

 aire not these empirical laws, but the 

 causal laws which explain them. The 

 empirical laws of those phenomena 

 which depend on known causes, and 

 of which a general theory can there- 

 fore be constructed, have, whatever 

 may be their value in practice, no 

 other function in science than that of 

 verifying the conclusions of theory. 

 Still more must this be the case when 

 most of the empirical laws amount, 

 even within the limits of observation, 

 only to approximate generalisations. 



§ 2. This, however, is not, so much 

 as is sometimes supposed, a peculi- 

 arity of the sciences called moral. It 

 is only in the simplest branches of 

 science that empirical laws are ever 

 exactly true, and not always in those. 

 Astronomy, for example, is the sim- 

 plest of all the sciences which ex- 

 plain, in the concrete, the actual 

 course of natural events. The causes 

 or forces on which astronomical phe- 

 nomena depend are fewer in number 

 than those which determine any other 

 of the great phenomena of nature. 

 Accordingly, as each efifect results 

 from the conflict of but few causes, a 

 great degree of regularity and uni- 

 formity might be expected to exist 

 among the effects ; and such is really 

 the case : they have a fixed order and 

 return in cycles. But propositions 

 which should express with absolute 

 correctness all the successive positions 

 of a planet until the cycle is com- 

 pleted would be of almost unmanage- 

 able complexity, and could be obtained 

 from theory alone. The generalisa- 

 tions which can be collected on the i 



subject from direct observation, even 

 such as Kepler's law, are mere ap- 

 proximations : the planets, owing to 

 their perturbations by one another, 

 do not move in exact ellipses. Thus 

 even in astronomy perfect exactness 

 in the mere empirical laws is not to be 

 looked for ; much less, then, in more 

 complex subjects of inquiry. 



The same example shows how little 

 can be inferred against the univer- 

 sality, or even the simplicity of the 

 ultimate laws, from the impossibility 

 of establishing any but approximate 

 empirical laws of the effects. The 

 laws of causation according to which 

 a class of phenomena are produced 

 may be very few and simple, and yet 

 the effects themselves may be so 

 various and complicated that it shall 

 be impossible to trace any regularity 

 whatever completely through them. 

 For the phenomena in question may 

 be of an eminently modifiable charac- 

 ter ; insomuch that innumerable cir- 

 cumstances are capable of influencing 

 the effect, although they may all do it 

 according to a very small number of 

 laws. Suppose that all which passes 

 in the mind of man is determined by 

 a few simple laws : still, if those 

 laws be such that there is not one of 

 the facts surrounding a human being, 

 or of the events which happen to him, 

 that does not influence in some mode 

 or degree his subsequent mental his- 

 tory, and if the circumstances of dif- 

 ferent human beings are extremely 

 different, it will be no wonder if very 

 few propositions can be made respect- 

 ing the details of their conduct or 

 feelings which will be true of ail 

 mankind. 



Now, without deciding whether the 

 ultimate laws of our mental nature 

 are few or many, it is at least certain 

 that they are of the above description. 

 It is certain that our mental states, and 

 our mental capacities and suscepti- 

 bilities, are modified, either for a time 

 or permanently, by everything which 

 happens to us in life. Considering, 

 therefore, how much these modifying 

 causes differ in the case of any two 



