“Some deny flatly the possibility of ever arriving at 
an understanding of the nature of life. But if we ask 
ourselves in what this understanding of the nature of life 
could consist, from the point of view of positive philos- 
ophy, we have no difficulty in recognizing that such an 
understanding must be reduced to comparing vital phe- 
nomena with some physico-chemical model already known, 
suitably modified by the particular special conditions im- 
posed upon it so that just these special conditions shall 
determine the differences which exist between this vital 
phenomenon and that phenomenon of the inorganic world 
most closely related to it. If this be so, it is then the duty 
of science emphatically to refuse to give up the attempt to 
understand the nature of living matter, for that would be 
to belie the Spirit of all scientific endeavor. For whether 
it be clearly recognized or not, it is just this search for the 
nature of the vital principle which properly constitutes the 
principal object and the final goal of all biologic study in 
general.”—E. RiGNANO, in “Acquired Characters,’ p. 
334- 
