4 Theory <f Agriadiure. [Jan., 



be done for agriculture. Here one of the early, though great 

 achievements, was the determination of the true motion of the 

 planets, from which has been deduced the universal law of 

 gravitation — a theory of universal application. But before this 

 great achievement could be effected, more than two thousand 

 years of observation were required. Such a period must elapse 

 before a just theory of the heavenly bodies could be proposed, 

 or before their mechanical adjustment could be understood. 

 Each observation must be regarded as a step to the accomplish- 

 ment of this end. Indeed truth, under whatever name it is 

 sought, whether astronomy, geology, or chemistry, or agricul- 

 ture, can only be attained in this way — that is, in a patient, 

 unprejudiced investigation. In the spirit of patience, then, we 

 may hope and expect that there is nothing too great to be at- 

 tempted, and nothing too minute, which may not be studied 

 with present profit, or with a prospective value. 



We have said that the true theory of agriculture is difficult 

 of attainment, in consequence of the complicated nature of the 

 questions which must first be solved in our experiments and 

 observations. This renders it necessary that we should dis- 

 engage it, as much as possible, from all extraneous questions : 

 all those which do not strictly belong to it. We must con- 

 sider it in its simplest aspect. We need not regard clima- 

 tology, for instance, as at all connected with the theory of ag- 

 riculture; so there are many questions in vegetable physiology 

 which are strictly special, and need not be taken into consider- 

 ation. 



A theory of agriculture, when reduced to the most general 

 expression, or what is the same thing, when comprised in one 

 or more formulas, should express the relation subsisting be- 

 tween the products of vegetation and the forces to which they 

 are due ; or to give another expression to an idea equally gen- 

 eral, they should express the mutual dependence subsisting be- 

 tween the vital functions of plants and the inorganic matters 

 which surround them. In such a formula would be comprised 

 a view of the origin of the products of organization, together 



