PREFACE. 
viii 
on ; but it has been less noticed that the men who thus occu- 
pied themselves in acquiring and forwarding a knowledge which 
many may deem purely ornamental, were the same individuals 
who were most engaged in the active discharge of the duties of 
their profession, and the most instrumental, to its advance. Boer- 
haave, Cullen, Hunter, Darwin and Jenner are very memorable 
instances of this fact, which is illustrated with lesser brilliancy 
in Lister, Sloane, Mead, Fothergill, Lettsom, Sims, Maton, in 
Withering of Birmingham, in Percival and Hull of Manches- 
ter, in Pulteney of Dorset, Stokes of Chesterfield, and nume- 
rous others whose names will occur to every one conversant with 
the history of medicine. This is only what on reflection might 
have been anticipated, for that very activity of mind and per- 
spicacity which originated and upheld their sagacity and suc- 
cess as practitioners, was sure to carry them far in whatever 
side-path the natural bent of their taste led them for the oc- 
cupation and entertainment of the leisure hours which the busi- 
est must have or may create. Idleness has no leisure. Were 
it necessary I might safely shelter myself under the cover of 
these exemplars, in the contemplation of whose lives I have of- 
ten nurtured my love to my profession, — and hence, perhaps, 
an ambition to follow them even at a far distance ; — but there 
never was a time when it was necessary to vindicate to any but 
the ignorant the erratic excursions of medical men into the fields 
of science and literature, for assuredly the rank which the pro- 
fession as a body has taken and holds in public estimation de- 
pends for its patent, in part at least, on the scientific and lite- 
ary character of its professors ; and by continuing to support 
that character they will best secure it from the vulgarity of a 
common mercature, or the selfishness of a venal quackery. 
Zoophytes present to the physiologist the simplest indepen- 
dent structures compatible with the existence of animal life, 
enabling him to examine some of its phenomena in isolation 
and free from the obscurity which greater complexity of anato- 
