DISCOVERY OF INSEPARABLE COINCIDENCES. 447 



be the cause of a phenomenon is sometimes shown to be 

 only a mere coincidence by the discovery of exceptional 

 cases ; a properly-stated cause has no real exceptions. 



The sum total of a dynamic phenomenon, reduced to 

 its simplest form, may be viewed as consisting of the 

 effect, its cause, static conditions, and inseparable coinci- 

 dences. 



CHAPTER XLIX. 



EXPLANATION OF RESULTS. 



A SCIENTIFIC investigator should possess the power of cor- 

 rectly interpreting effects ; of detecting fallacy when in 

 the guise of truth, and of recognising truth when inter- 

 mixed with error. The power of quickly perceiving the 

 true explanations of new physical and chemical pheno- 

 mena is a most comprehensive one, and very difficult to 

 attain, and that which characterises chiefly a great dis- 

 coverer ; it also requires a greater combination of mental 

 powers, and a larger degree of exercise of the reasoning 

 faculty, than any other part of original research. Com- 

 parison must precede inference. We cannot draw in- 

 ferences respecting phenomena unless we can perceive 

 likeness or difference; we cannot recognise real likeness 

 or difference unless we possess an accurate knowledge of 

 and are familiar with the facts to be compared ; and we 

 cannot possess that knowledge and be familiar with those 

 facts unless we have had extensive mental contact with 

 them ; and as the truths of science are almost infinite in 

 number, accurate and familiar knowledge of even a small 

 portion of them requires great reading and experience. 

 There are also many ways of observing, and many aspects 



