KNOWLEDGE, EXPLANATION, & c . 529 



^S^^3 



is but the starting-point for the discovery of ex 



e 



There is probably no science, I have said which is 

 entirely free from empirical and unexplained facts Wo 

 approaches most nearly to this position, as if is merety a 



variar ''' ", p s , sesses the least Mmter of distinct logical 

 vanataom, and the greatest number of logical equivalents 



classes^ ," ? amon S .P r Pitions involving three 

 classes (p 141), is a case m point g , h 



discovered by Professor Clifford that in regard to statements 

 involving four classes, there is only one exampeo? two 

 dissimilar statements haviag the S aL disS (p .4^) 



or negative character of quantities, as in De Morgan's 

 theorem concerning negative areas. 



Accidental Discovery. 



There are not a few cases where almost pure accident 

 has determined the moment when a new branch of know 



% 



not correspond with the external facets of the crystal 

 great many more crystals were soon broken intTntio 



1 De Morgan's Budget of Paradoxes, p. 291. 



M M 



