4 SELECTION OF EXPERIMENT. 



research. In a thousand instances, which will occur as 

 you proceed, you must do more than gaze and wonder ; 

 the rudest peasant can do that: you must inquire, 

 must investigate, must have recourse to reasoning, to 

 observation, to experiment. 



Take, for example, a grain of mustard-seed and a 

 grain of gunpowder; is there any thing in the colour, 

 size, weight, or other sensible qualities of these respec- 

 tive substances which would enable you, in limine, to 

 predict that a spark falling upon a heap of the one 

 would be extinguished, while if it had fallen upon a 

 heap of the other, it would have produced sudden and 

 destructive conflagration ? No : this knowledge is not 

 a result of passive inspection, however patient. But 

 the youngest boy that ever fired off a squib or a cracker, 

 and knew something of its structure or composition, from 

 that moment ascertains an important quality of detona- 

 ting substances; nor ever after will you detect him, 

 child as he may be, loading a pistol with mustard-seed, 

 or sowing gunpowder in a garden. 



A single experiment, then, happily selected or care- 

 fully conducted, may lead to a momentous discovery; 

 yet, in the usual routine of scientific deduction, it is 

 advisable, nay, it is often necessary, to trace our way by 

 a cautious and judiciously conducted process. It may, 

 indeed, be laid down as a universal maxim, that there is 

 no infallible, and at the same time, easy method of 

 attaining either excellence or eminence. There are no 

 by-paths to the temple of philosophy. The small 

 portion of learning or science which is attainable by the 

 help of facilitating expedients, is but a temporary, as 

 contrasted with a durable edifice a tent contrasted with 

 a castle. It is as unreasonable to hope to acquire 



