[ iii ] 
PREFACE. 
2" HAT a Man write well % for the Be- 
nefit and Information oj the Publick , it 
is requifite that the Subject be of his own 
Option , and not by Gompulfion ; a?id that he 
he as far acquainted with what he treats of 
as his Situation and Opportunities can enable 
him * 
Thus , in the vegetable Kingdom , many 
learned Men, in feveral Ages , have applied 
themfelves to the Study of the Nature , Prin- 
ciples , Virtues , and Ufes of fome particular 
Plants , defpairing of a fuccefsful Undertak- 
ing of the Whole . But if feveral Authors 
treat of the fame Vegetable , they Jhould be 
fure 3 either that each is able to cajl fome 
A new 
