THEORIES OF THE OPERATION OF THE SOIL. 397 



soil had probably become exhausted by sinking down, through 

 its greater specific gravity j but I could not see that there could 

 be any difficulty in the plants reaching it, where the whole body 

 of lime lay within so short a distance of the surface. My own 

 belief is, that, in this case, its operation is chiefly mechanical, 

 and that its use was merely to consolidate the upper surface, and 

 make it more adhesive for the roots of the plant, and that any 

 other substance or marl, equally firm and consistent, would have 

 served the same end. 



One of the most eminent chemists of the present day, distin 

 guished for the splendor of his attainments, seems to entertain, 

 with no small confidence, the opinion that chemistry, including 

 probably electricity and galvanism, is destined to solve all the 

 secrets of vegetable and animal life ; that the various processes 

 going on in nature are mere chemical processes ; and that any 

 thing like a vital power above or beyond them all, and incapable 

 of being solved by scientific investigation, is an hypothesis 

 unworthy of an enlightened mind. It is certainly not for the 

 human mind, as yet, to say what cannot be done ; and it would 

 be quite premature for Science to assume that she has reached 

 the ultimate boundaries of investigation, as it would be impious 

 for her to claim the prerogatives of omniscience. But if I may 

 in the case adventure the remark, admiring as much as any one 

 can the actual and wonderful achievements of science, there 

 still remains beyond even the farthest advances an impassable 

 barrier, a terra incognita, which the most adventurous have not 

 yet penetrated. It is easy to ascertain that certain substances 

 have an affinity for each other, and science, with wonderful 

 ingenuity, has determined the forms of combination under which 

 they become united. The action or force by which they are 

 brought together and there held may hereafter be explained, and 

 may be ranked under some unknown chemical force ; but as yet 

 any attempts to define, or even conjecture, its nature, have been 

 wholly abortive. The simple and familiar fact, that the muscles 

 are obedient to the will in moving the limbs, every one admits ; 

 but in what this will consists, and how it is exerted, and how it 

 effects its purpose, seems as yet as far from being reached, as on 

 the day that the first child was born into the world. 



We are very apt to exclaim, in the ecstasy of the Grecian phi 

 losopher in the successful investigation of an interesting prob- 

 34 



