342 CHANGES BY TIME. 



germes of plants or of animals, till we find them de- 

 veloped in visible and tangible embryos, we must 

 not make our ignorance the measure of nature's 

 working ; for though we have seen them come only 

 in one way, and, generally speaking, perish in an- 

 other, we are not to suppose that that is all. When 

 forests of one kind of timber are cut down, new- 

 plants make their appearance ; and there are evi- 

 dences that races, both of plants and of animals, 

 have perished even in our own country, without 

 any great convulsion of nature, for their remains 

 have been left on the strand, and buried by the slow 



Progress of the depositation of the matter washed 

 own by the rains and stayed by the reaction of the 

 waves. 



Cultivation itself will deteriorate and in time 

 destroy races, if the same race, and the same mode 

 of culture be pursued amid general change. Our 

 own times are times of very rapid change, and, upon 

 the whole, of improvement ; we dare not, without 

 the certainty of their falling off, continue the same 

 stock and the same seed-corn, season after season, 

 and age after age, as was done by our forefathers. 

 The general change of the country must have change, 

 and not mere succession, in that which we cultivate ; 

 and thus we must cross the breeds of our animals, 

 and remove the seeds and plants of our vegetables 

 from district to district. 



There is something of the same kind in human 

 beings, and we kave reason to expect that there 

 should; because, in as far as man is material and 

 mortal, he is just as dependent upon circumstances 

 as any other material production. Hence we find 

 that when a town or a district is busy and bustling, 

 and strangers resort to it, both the population and 

 the energy increase far faster than the numerical 

 addition of strangers. But, on the other hand, when 

 it becomes dull, and strangers cease to resort to it, 

 it dies away, both in population and in mental energy, 



