438 THE POPULAR SCIENCE MONTHLY. 



courses, a sad state of feeling is produced, and many mistakes are 

 likely to follow. 



Sir William Hamilton's definition of science has for genus " a com- 

 plement of cognitions," and for differentia " logical perfection of 

 form," and " real truth of matter." The definition is a demand for a 

 certain fullness. We can only conjecture, in the case of any particu- 

 lar science, how much knowledge such a man as Sir William Hamil- 

 ton would regard as a " complement." But stiidents of science do 

 well to remind themselves that it is impossible to exceed, and very 

 difficult to succeed, and the easiest thing imaginable to fall short. In 

 other words, we have never been able to collect more material of 

 knowledge than the plan of any temple of science could work in, and 

 really did not demand for the completion of the structure, and that 

 very few temples of science have been finished, even in the outline, 

 while all the plain of thought is covered by ruins of buildings begun 

 by thinkers, but unfinished for want of more knowledge. Even where 

 there has been gathered a sufficient amount of knowledge to be 

 wrought by the logical understanding into the form of a science, so 

 that such a mind as Hamilton's would admit it as a science i. e., a 

 sufficient complement of cognitions of truths put in logical form an- 

 other age of labor, in other departments, would so shrink this science 

 that, in order to hold its rank, it would have to v:iork in the matter of 

 more knowledge, and, to preserve its symmetry, be compelled to re- 

 adjust its architectural outlines. In other words, what is science to 

 one age may not be science to its successor, because that successor 

 may perceive that, although its matter had the character of real truth, 

 and its form the character of logical perfection, as far as it xoent, nev- 

 ertheless, there were not enough cognitions ; not enough, just because 

 in the later age it was possible to obtain additional cognitions, which 

 could not have been obtained earlier. 



And, in point of fact, has not this been the history of each of the 

 acknowledged sciences ? And can any significance be assigned to 

 Sir William Hamilton's definition without taking the word " comple- 

 ment " to mean all the cognitions possible at the time f Now, unless 

 at one time men have more cognitions of any subject than at another 

 time, one of two things must be true : either (1) no new phenomena 

 will appear in that department, or (2) no abler observer will arise. 

 But the history of the human mind in the past renders both supposi- 

 tions highly improbable. If no new phenomena appear, we shall have 

 observers abler than have existed, because, although it were granted 

 that no fresh accessions of intellectual power came to the race, each 

 new generation of observers would have increased ability, because 

 each would have the aid of the instruments and methods of all prede- 

 cessors. When we go back to consider the immense labor performed 

 by Kepler in his investigations which led to his brilliant discoveries, 

 we feel that if his nerves had given way under his labors, and domes- 



