The doctrine of the conservation of energy tells neither one way nor the
other [on the doctrine of immortality]. Energy is the cause of movement
of body, i.e. things having mass. States of consciousness have no mass,
even if they can be conceded to be movable. Therefore even if they are
caused by molecular movements, they would not in any way affect the
store of energy.
Physical causation need not be the only kind of causation, and when
Cabanis said that thought was a function of the brain, in the same
way as bile secretion is a _function_ of the liver, he blundered
philosophically. Bile is a product of the transformation of material
energy. But in the mathematical sense of the word "function" thought
may be a function of the brain. That is to say, it may arise only when
certain physical particles take on a certain order.
By way of a coarse analogy, consider a parallel-sided piece of glass
through which light passes. It forms no picture. Shape it so as to be a
bi-convex, and a picture appears in its focus.
Is not the formation of the picture a "function" of the piece of glass
thus shaped?
So, from your own point of view, suppose a mind-stuff--[--Greek--]--a
noumenal cosmic light such as is shadowed in the fourth gospel. The
brain of a dog will convert it into one set of phenomenal pictures, and
the brain of a man into another. But in both cases the result is the
consequence of the way in which the respective brains perform their
"function."