INTRODUCTION. 
87 
■of the future fly, which is gradually developed by 
the accretion of new matter ; and its various enve- 
lopes are thrown off as they successively become su- 
perflcial, till it is fully matured and perfected. When 
in the state of pupa, the embryo having then advanced 
another stage towards completion, the parts of the 
perfect insect are even more easily discerned than 
in the previous condition ; and for some time before 
the final change they may even be perceived through 
the membrane in which they are enclosed. 
Even when viewed in this light, as a series of de- 
velopments without any absolute change of identity, 
the metamorphoses of these creatures are sufficiently 
wonderful to be ranked among the most remarkable 
and interesting natural operations with which we are 
acquainted. So striking did they appear to the an- 
cients, that they regarded the butterfly as affording 
a most lively and beautiful emblem of the soul ; and 
according to this idea, the Greeks often used the 
word Psyche, which properly means the human soul, 
to signify also a butterfly. With greatly more ac- 
curate notions of the real nature of these transfor- 
mations, few modern writers on the subject have 
failed to notice and dilate upon the general symbo- 
lical analogy which subsists between them and the 
changes which the human body is destined to un- 
dergo. The caterpillar — chiefly occupied in pro- 
viding for its bodily wants and appetites — is regard- 
ed as representing the ordinary condition of human 
life ; the chrysalis the intermediate state of death ; 
