290 PERSONAL PREPARATION FOK RESEARCH. 



unquenchable love of truth. A scientific investigator 

 should love truth with unceasing fervour, and avoid error 

 with all his might, and unless he does so he will not be 

 able to make many important discoveries. This state- 

 ment does not, however, mean that the love alone of truth 

 is sufficient to enable a man to make discoveries, but only 

 that it is one of the necessary motives and conditions. 



We cannot intelligently love that which we cannot 

 form an idea of, nor discover that which we cannot dis- 

 criminate when it is present ; and if we cannot discri- 

 minate truth, we cannot intelligently love it, nor can we 

 discover it. This raises the question, what is truth ? and 

 how can we detect it ? questions which have occupied the 

 minds of men during many ages, and even now are only 

 partially solved. These questions have been already dis- 

 cussed in Chapter XIII. ' on the Criteria of Scientific 

 Truth ' ; and I have there shown, and also in Chapter 

 XXXVI. on < the Use of the Intellect in Scientific Kesearch,' 

 that scientific truth is that which is universally consistent 

 with nature, and that the intellect in general, and the 

 reasoning power in particular, is the sole means by which 

 we apprehend, distinguish, and select truthful ideas. What, 

 therefore, is worthy of love and pursuit, the intellect (act- 

 ing upon the evidence supplied by the external world and 

 our own faculties) decides for us. 



The love of truth and its beneficent effects, and the 

 fear of error and its evil consequences, are the purest 

 motives of human action, because they do not excite selfish 

 expectations or unreasonable desires ; and to employ un- 

 regulated lower motives in the pursuit of pure science, 

 would be to use inferior means to effect a good object. 



Scientific investigators are also stimulated by the same 

 general cause which excites most men to devote themselves 

 to other occupations, viz., the health and pleasure deriv- 



