INTRODUCTION. 



WE now arrive at that study which offers the 

 most copious and complete example of the 

 sciences of classification, I mean Botany. And in 

 this case, we have before us a branch of knowledge 

 of which we may say, more properly than of any of 

 the sciences which we have reviewed since Astro- 

 nomy, that it has been constantly advancing, more 

 or less rapidly, from the infancy of the human race 

 to the present day. One of the reasons of this 

 resemblance in the fortunes of two studies so widely 

 dissimilar, is to be found in a simplicity of principle 

 which they have in common ; the ideas of Likeness 

 and Difference, on which the knowledge of plants de- 

 pends, are, like the ideas of Space and Time, which 

 are the foundation of astronomy, readily appre- 

 hended with clearness and precision, even without 

 any peculiar culture of the intellect. But another 

 reason why, in the history of botany, as in that of 

 astronomy, the progress of knowledge forms an 

 unbroken line from the earliest times, is precisely 

 the great difference of the kind of knowledge which 

 has been attained in the two cases. In astronomy, 

 the discovery of general truths began at an early 

 period of civilization ; in botany, it has hardly yet 

 begun ; and thus, in each of these departments of 

 study, the lore of the ancient is homogeneous with 



