479 



can be understood. The human understanding has its limits, doubtless, 

 beyond which it cannot pass ; but how far is it at present from having 

 reached them ? Every day is disclosing to us some new truth. Many 

 things, once enveloped in all the terrors of mystery, arc now familiar 

 to the understanding of a child. The works of God and the courses of 

 his providence, are not so many isolated facts, but they are facts com- 

 pacted together, and under the control of general laws ; so that, beyond 

 all question, many of the most extraordinary phenomena, which present 

 themselves in nature, are explicable upon the simplest principles. In 

 many cases a single key will open the most complicated lock, and is at 

 the same time applicable to a thousand others. The discussions of Lie- 

 big furnish some beautiful illustrations of these principles. 



In order to solve the secrets of vegetable life and growth, we must 

 watch the plant from its germination to its maturity, and i-emark, with 

 all possible exactness, the vai'ious influences which bear upon it. We 

 must study its nature, its relations, its changes ; its relations to the soil, 

 to the climate, to the light, to the moisture, and to its whole culture. 

 Botany, considered as a mere form of classes and a mere catalogue of 

 arbitrary names, is a meagre and comparatively worthless science ; but 

 when it involves the whole physiology of plants in all their aspects and 

 conditions, in their growth, culture, maturity, and uses, it becomes a 

 profound philosophy. Chemistry, likewise, must here come to our aid. 

 In order to know what the plant needs, we must know what it is com- 

 posed of; in order to learn what it obtains from the soil, we must as- 

 certain what the soil has to yield to it ; and we must consider the con- 

 dition of the plant, in reference to the condition of the soil in which it 

 is planted. Manures, likewise, everywhere the acknowledged means 

 of fertility, require the most exact examination. Ascertaining, by the 

 aid of chemical inquiry, the elements of the plant, we shall at least 

 learn something of what it requires ; ascertaining the nature of the soil, 

 we shall see how it is suited to the plant cultivated ; and knowing the 

 composition of the manures, we may come to understand their opera- 

 tions. Chemical analysis seems to offer the only means of solving these 

 mysteries. 



It has already made distinguished advances ; but yet they can be re- 

 garded only as first steps. Thei'c are difEculties in the case, which it 

 would be in vain to deny. All chemical analyses are necessarily des- 

 tructive of the subjects to which they arc applied. We cannot take the 

 separate elements from the analysis of a plant, a manure, or a soil, and 

 put them together again like the pieces of a dissected map. We can 



