XVI INTRODUCTION. 



It may perhaps be urged, that the Natural System is still in so 

 unsettled a state, that botanists disagree among themselves about the 

 limits and relative position of the orders ; an argument to which 

 some weight undoubtedly attaches. But, at the same time, it must 

 be remarked, that all sciences of observation proceed towards a 

 settled state by slow degrees; that Botany is one upon which 

 there is at least as much to learn as is at present known ; and 

 that the differences of opinion, just alluded to, affect the orders 

 themselves but little, and the principles of the science not at all, 

 but apply rather to the particular series in which the orders should 

 stand with relation to each other — a point which is not likely to 

 be settled at present, and which is of very little importance for 

 any useful purpose. 



The last kind of difficulty, and the only one of which I admit 

 the force, is the want of an introductory work upon the subject; and 

 this, I presume to hope, will be diminished by the appearance of the 

 present publication. 



The principle upon which I understand the Natural System of 

 Botany to be founded is, that the affinities of plants may be deter- 

 mined by a consideration of all the points of resemblance between 

 their various parts, properties, and qualities ; and that thence an 

 arrangement may be deduced in which those species will be placed 

 next each other which have the greatest degree of relationship ; and 

 that consequently the quality or structure of an imperfectly known 

 plant may be determined by those of another which is well known. 

 Hence arises its superiority over arbitrary or artificial systems, such 

 as that of Linnaeus, in which there is no combination of ideas, but 

 which are mere collections of isolated facts, not having any distinct 

 relation to each other. 



This is the only intelligible meaning that can be attached to the 

 term Natural System, of which Nature herself, who creates species 

 only, knows nothing. It is absurd to suppose that our genera, orders, 

 classes, and the like, are more than mere contrivances to facilitate 

 the arrangement of our ideas with regard to species. A genus, 

 order, or class, is therefore called natural, not because it exists in 

 Nature, but because it comprehends species naturally resembling 

 each other more than they resemble any thing else. 



The advantages of such a system, in applying Botany to useful 

 purposes, are immense, especially to medical men, with whose pro- 

 fession the science has always been identified. A knowledge of the 

 properties of one plant is a guide to the practitioner, which enables 

 him to substitute some other with confidence, which is naturally 

 alhed to it ; and physicians, on foreign stations, may direct their 



