20 INTRODUCTORY EXPLANATIONS. 



to arrange and generalise them, and to apply precise tenns 

 and fonmilas for expressing the arrangements and generali- 

 sations. So fai- as yet earned, the result may now easily 

 be learned and understood, and hereafter will probably be 

 much extended and improved upon by other parties ; but 

 the time and thought really required for collecting together 

 and compaiing the imconnected facts, in order to reduce 

 them into some sort of orderly arrangement, can be con- 

 ceived only by those who have themselves taken up a chaos 

 of facts, and reduced them mto science. This remark is 

 not penned in silly boast, but simply in record of a single, 

 and perhaps not very important, event in the history of 

 British botany.. 



In justification of the author's right to call the past a 

 " chaos," and his own pages an attempt to substitute science 

 instead, he will ventiure on an apparent digression here ; 

 although, as the sequel may show, it is but another route to 

 the same end — the botanical-natmal divisions of Britain. 

 " Science," writes Sir Jolm Herschel, " is the knowledge of 

 many, orderly and methodically digested and arranged, so 

 as to become attainable by one." If this definition is cor- 

 rect, — and it has frequently been quoted with approval, — 

 it is not the knowledge of simple facts, but their mental 

 digestion and anangement which constitute science. 



An-angement is the first effort of science. What is next 

 requu-ed ? The same philosopliical writer, just quoted, un- 

 mediately proceeds to define natural science as being the 

 " knowledge of causes and their effects, and of the laws of 

 nature." Now, it cannot be said that a knowledge of plants, 

 as species, or an anangement of them into groups of re- 

 sembling species, under the designation of orders and ge- 

 nera, is a " knowledge of causes and their effects, and of 

 the laws of nature." Neither can it be said that, to ascer- 

 tain the areas over which species extend, and then- census 



