50 LIFE: ITS ORIGIN AND NATURE 
the nervous currents, which play to-and-fro in 
the higher centres of the cerebral cortex. He 
coined the term “Epiphenomenon” to express 
or signify this by-product, so to say, of brain 
activity. The difficulty with this theory is 
that, for us, the important thing is the shadow 
and not the horse! And it is also difficult to 
explain why such a mere by-product should 
ever have come into being in the process of 
evolution. Furthermore, the specific character 
of the relationship between these two (mind 
and brain) is not in the least explained by this 
formula. It merely states the facts. The pri¬ 
mary question still remains: How can a par¬ 
ticular thought (apparently a non-material 
thing) and a particular brain-change (a ma¬ 
terial thing) be related one to another? 
Professor Tyndall saw this difficulty very 
clearly, and, in his “Fragments of Science” 
stated the problem thus: 
“The passage from the physics of the brain 
to the corresponding facts of consciousness 
is unthinkable. Granted that a definite thought 
and a definite molecular action in the brain oc¬ 
cur simultaneously, we do not possess the in¬ 
tellectual organ, nor apparently, any rudiment 
of the organ, which will enable us to pass, by a 
process of reasoning, from the one to the other. 
Were our minds and senses so expanded, 
strengthened and illuminated as to enable us to 
see and feel the very molecules of the brain; 
were we capable of following all their motions, 
all their groupings, all their electrical dis¬ 
charges, if there be such; and were we inti¬ 
mately acquainted with the corresponding 
