GENERAL 11ETROSPECT. 741 



>vcries, and nourishing hopes the fallacy of which often 

 mtinues long undetected, each age dreams that it has 

 approximated closely to the culminating point of the recog- 

 nition and comprehension of nature. I doubt whether, on 

 serious reflection, such a belief will tend to heighten the 

 enjoyment of the present. A more animating ^..nviction, and 

 one more consonant with the great destiny of cai race, is, that, 

 the conquests already achieved constitute only a very incon- 

 siderable portion of those to which free humanity will attain 

 in future ages by the progress of mental activity and general 

 cultivation. Every acquisition, won by investigation, is 

 merely a step to the attainment of higher things in the event- 

 ful course of human affairs. 



That which has especially favoured the progress of know- 

 ledge in the nineteenth century, and imparted to the age its 

 principal character, is the general and beneficial endeavour 

 not to limit our attention to that which has been recently 

 acquired, but to test strictly, by measure and weight, all 

 earlier acquisitions ; to separate certain knowledge from mere 

 conjectures founded on analogy, and thus to subject every 

 portion of knowledge, whether it be physical astronomy, 

 the study of terrestrial natural forces, geology, or archaeology, 

 to the same strict method of criticism. The generalisation of 

 this course has, most especially, contributed to show, on each 

 occasion, the limits of the separate sciences, and to discover 

 the weakness of certain studies in which unfounded opinions 

 take the place of certain facts, and symbolical mvths mani- 

 fest themselves under ancient semblances as grave theories. 

 Vagueness of language, and the transference of the nomen- 

 clature of one science to another, have led to erroneous views 

 and delusive analogies. The advance of zoology was long 

 endangered, from the belief that, in the lower classes of ani- 

 mals, all vital actions were attached to organs similarly 

 formed to those of the higher classes. The knowledge of the 

 history of the development of plants in the so-called Crypto- 

 gamic Cormophytes (mosses and liverworts, ferns, and lyco- 

 podiacerc), or in the still lower Thallophytcs (algoe, lichens, 

 and fungi), has been still more obscured by the supposed 

 general discovery of analogies with the sexual propagation 

 of the animal kingdom.* 



* Schleiden, Grundzune der wissensclia/tlichen Botanik, th. i. 1845, 



