1396.] “ 4 New Factor in Evolution.” 701 
companies perfect use of our faculties, and pain their impeded 
use. The philosophy which prevailed after Aristotle was 
dominated by the Oriental superstition that the forces of this 
world are divided between the Powers of Good and of Evil. 
How this superstition seized upon and biased the dogmas of 
our theologic ancestors until belief in a personal Devil was uni- 
versal among even the learned in the middle ages, is a matter 
of undisputed history. Aristotle’s doctrine fitted well with 
this superstition, and his unquestioned authority enforced its 
universal acceptance. Thus, as late as 1647, we have Descartes, 
the highest authority of his age, declaring that “ All our 
pleasure is nothing more than the consciousness of some one 
or other of our perfections.” When Science dawned, and began 
basing mental activities upon correspondent neural processes, 
nothing was easier or more inevitable than that the doctrine 
which always had been conceded to express general conditions 
of welfare and activity should be transferred to general 
conditions of the nervous system; and that, in general, 
“ heighted neural discharge” should be declared to be the basis 
of pleasure, and the reverse to be the basis of pain. Thus, an 
early conjecture of Aristotle, fostered by one of the grossest 
theological superstitions, and transformed, as I shall show, by 
most uncritical and fallacious physiological assumptions, is 
the historic origin of what Prof. Baldwin calls “A New 
Factor in Eyolution.® 
The origin of the notion having been accounted for inde- 
pendently of any critical regard of the facts, we will now 
examine it in the light of the facts. We have no means of 
examining;neural discharges directly, or independently of their 
‘stimuli, their sensory effects, and their motor results; we have 
no other means of measuring them, except through analogy 
with the strength of these. In general it is fundamentally 
observed that where the stimulus is intense the sensation is in- 
tense. Also, muscular reaction is proportional to the stimulus 
and to the sensation. Every known fact, outside of the phe- 
nomina of pain and pleasure in dispute, conforms to the in- 
3 Whether it is with reference to Spencer, Bain, Descartes or Aristotle, that 
this factor is “new,” Prof. Baldwin does not state. 
