GENERAL RETROSPECT. 355 



tion, such a belief will tend to heighten the enjoyment of the 

 present. A more animating conviction, and one more conso- 

 nant with the great destiny of our race, is, that the conquests 

 already achieved constitute only a very inconsiderable por- 

 tion 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 eventful course of human 

 affairs. 



That which has especially favored the progress of knowl- 

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

 principal character, is the general and beneficial endeavor not 

 to limit our attention to that which has been recently acquir- 

 ed, but to test strictly, by measure and weight, all earlier ac- 

 quisitions ; to separate certain knowledge from mere conject- 

 ures 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 generalization 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 myths manifest themselves 

 under ancient semblances as grave theories. Vagueness of 

 language, and the transference of the nomenclature 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 animals, all vital actions 

 were attached to organs similarly formed to those of the 

 higher classes. The knowledge of the history of the develop- 

 ment of plants in the so-called Cryptogamic Cormophytes 

 (mosses and liverworts, ferns, and lycopodiaceee), or in the still 

 lower Thallophytes (algse, lichens, and fungi), has been still 

 more obscured by the supposed general discovery of analogies 

 with the sexual propagation of the animal kingdom.* 



If art may be said to dwell within the magic circle of the 

 imagination, the extension of knowledge, on the other hand, 

 especially depends on contact with the external world, and 

 this becomes more manifold and close in proportion with the 

 increase of general intercourse. The creation of new organs 

 (instruments oi observation) increases the intellectual and nol 



* Schleideu, Grundzuge der wissenschaftlichen Botanik, th. i., 184.^ 

 s. 152, th. ii., 8. 7Q ; Kunth, Lehrbnch der Botanik, th. i., 1847, s. 91-10(i 

 and 505. 



