514 LOGIC OF THE MORAL SCIENCES. 



they have a fixed order, and return in cycles. But 

 propositions which should express, with absolute cor- 

 rectness, all the successive positions of a planet until 

 the cycle is completed, would be of almost unmanage- 

 able complexity, and could be obtained from theory 

 alone. The generalizations which can be collected on 

 the subject from direct observation, even such as 

 Kepler's law, are mere approximations : 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 universality or even the simplicity of the 

 ultimate laws, from the impossibility of establishing 

 any but approximative 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, extending completely through 

 them. For the phenomena in question may be of an 

 eminently modifiable character; insomuch that innu- 

 merable circumstances are capable of influencing the 

 effect, although they rhay all do it according to a very 

 small number of laws. Suppose that all which passes 

 in the mind of 1 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 history, and if 

 the circumstances of different human beings are 

 extremely different, it will be no wonder if very few 

 propositions can be made respecting the details of 



