254 president's address — section j. 



of mind which he may otherwise possess. Or if the physiologist in- 

 cludes neuro-psychology within his province, as he frequently does, he 

 is a psychologist as well as a physiologist ; and the problem is to show 

 the correlation between his material facts and the very different facts 

 of mind. We do not become acquainted with mind by concentrating 

 our attention on matter. It requires for its study special methods, 

 and notably the method of introspection. 



(3) When it is said that mental action is a form of energy, like heat, 

 light, or electricity, we are introduced to the doctrine of the conserva- 

 tion of energy. Without energy, actual or potential, matter has no 

 existence ; and the theory tells us that, though energy may flow into 

 diverse forms, the sum of energy throughout the material universe is 

 constant. Visible motion may be transformed into heat, and beat 

 again into visible motion, and so on through the whole round of the 

 forms of energy ; but in the system of the universe nothing is lost. It 

 is evident that this great generalisation is intended to apply only to a 

 material system. It has been verified by physical experiments, and, 

 since it is held that every form of energy is, at bottom, a mode of motion, 

 it follows from what has been already said that the law cannot be applied 

 to mind. When we try to decipher the connection between mind and 

 matter it is impossible to establish that equivalence which, according 

 to the law of the conservation of energy, prevails between material 

 cause and material effect. A sensation of sound, which is a mental 

 fact, is consequent on a stimulus imparted to the organ of sense. But 

 how is it possible, comparing the sensation with its immediate physical 

 condition or concomitant, to say that these two things are equivalent, 

 in the same way that a given amount of heat and a given amount of 

 visible motion are equivalent and interchangeable ? I will to move 

 m^' arm, and the arm is moved ; how can an equivalence be shown 

 between the volition and the changes which take place in neuron 

 or in muscle ? How, then, can the conservation of energy be cited 

 in favor of the statement that mind is a form of energy ? The 

 procedure of Haeckel on this point is simplicity itself. He shows that 

 matter and energy are inseparable. He then takes the liberty of 

 substituting mind, spirit, or thought for energy. ((7) And, in so doing, 

 he assumes that mental process is either identical with, or a special 

 form of, physical energy. The assumption is unwarrantable. The 

 transition from energy as a fact which characterises the material 

 world to the quite incomparable fact of mental change is no better 

 than a verbal juggle, and the only marvel is that anyone has succeeded 

 in deluding himself by so transparent an artifice. 



(4) What, again, is meant by the statement that mind is a function 

 of the brain ? The idea is that every bodily organ has its office or 

 function, and that it is the office of the brain to grind out mental facts. 

 To this it must be objected that, in describing any organic function, 

 we are describing the organ itself at work, and that we are going far 

 beyond any function of this kind when, instead of conffiiing ourselves 

 to the working of the brain, we ascrib e to it the power of generating 



(g) See " The Riddle of the Universe," pp. 21, 220. 



