IV 
PREFACE. 
extensive signification, is inseparable the knowledge 
of the various ways in which the laws of vegetable 
life are applicable to the augmentation of the luxuries 
and comforts, or to the diminution of the wants and 
miseries, of mankind. It is by no means, as some 
suppose, a science for the idle philosopher in his 
closet ; nor is it merely an amusing accomplishment, 
as others appear to think ; on the contrary, its field 
is in the midst of meadows, and gardens, and forests, 
on the sides of mountains, and in the depths of mines, 
— wherever vegetation still flourishes, or wherever it 
attests by its remains the existence of a former world. 
It is the science which converts the useless or noxious 
weed into the nutritious vegetable ; which changes a 
bare volcanic rock into a green and fertile island ; 
and which enables the man of science, by the powder 
it gives him of judging how far the productions of 
one climate are susceptible of cultivation in another, 
to guide the colonist in his enterprises, and to save 
him from those errors and losses into which all such 
persons unacquainted with Botany are liable to fall. 
This science, finally, it is which teaches the physician 
how to discover in every region the medicines that 
are best adapted for the maladies prevalent in it ; 
and which, by furnishing him with a certain clue to 
the knowledge of the tribes in which particular pro- 
perties are, or are not, to be found, renders him as 
much at ease, alone and seemingly without resources, 
in a land of unknown herbs, as if he were in the midst 
of a magazine of drugs in some civilised country. 
The principles of such a science must necessarily 
be complicated, and in certain branches, which have 
only for a short time occupied the attention of ob- 
servers, or which depend upon obscure and ill-under- 
stood evidence, are less clearly defined than could be 
