4 THE PROGRESS AND SPIRIT OF 



and which give certainty of other and similar attainments in 

 time yet to come. 



Admitting that hypothesis, and this often of adventurous 

 kind the f animi jactus liber ' - blends itself largely with 

 the recent progress of physical science, we would in no way 

 impugn this powerful instrument and aid of research ; the 

 use of which, under due limitation, is justified equally by 

 reason and experience. In all enquiries of this nature, ex- 

 cept those strictly mathematical, certainty and conjecture 

 necessarily and closely commingle. The speculation or bare 

 analogy of one day becomes the scientific induction of the 

 next ; and even where hypothesis is not thus happily fated, 

 it still has often high value as an interpreter and provisional 

 guide to the truths sought for. All sciences, and very espe- 

 cially those of optics, chemistry, and electricity, furnish notable 

 instances to this effect ; and have rescued hypothesis, in the 

 philosophical sense of the term, from the reproach which it 

 was once the fashion to cast upon it. Such vindication, how- 

 ever, affords no sanction to that spirit which pushes mere 

 speculation far in advance of experiment and observation, 

 and adventures rashly into fields not prepared for human 

 culture, if indeed ever accessible to it. Eccentric theories 

 of this kind, the produce of imperfect knowledge or illogical 

 understanding, will ever be found in the path of science ; 

 perplexing, it may be, to those who loosely follow it ; but 

 disappearing one after another, as truth pursues its steady 

 course amidst them. The mysteries of organic life, ap- 

 proached with caution by the true philosopher, are an es- 

 pecial seduction to these framers of new systems ; systems 

 which it becomes easy to coin, under shelter of a vague 

 phraseology, and aided by the very obscurity of the sub- 

 ject with which they deal. 



While speaking thus generally on the spirit and methods 

 of modern science, we may notice the fact, that there is 



