262 INNER VATION. [CHAP. X. 



however, who preserve their intellectual vigour to a very advanced 

 period of life, and in such persons, doubtless, the brain does not ex- 

 hibit any evidence of shrinking. It is during the period of greatest 

 mental activity and power that the brain acquires arid maintains its 

 highest point of development, that is, between the ages of twenty 

 and sixty. 



Whilst there is an evident connexion between a large quantity 

 of. cerebral matter, and a highly developed intellect, the quality of 

 the mind and that of the brain substance may also be supposed to 

 have a close relation to each other. For great power of action a 

 large muscle is needed, but for vigorous and well-adjusted muscular 

 movement a certain quality of fibre is also necessary to give full 

 scope to the nervous power (see pp. 1858 90). It is impossible 

 to determine what this peculiarity in quality is, but some idea of 

 the great influence which it may possess in the exercise of the two 

 great vital forces, the muscular and nervous, may be gained from 

 comparing the energy and action of a well-bred horse with those 

 of one which, in the language of the turf, shews little or no breed- 

 ing. The actual amount of muscular or nervous fibre may be the 

 same in both, or it may be less in the horse of good breeding 

 than in the other, yet the former does his work and endures fatigue 

 better. 



The nature of the connexion between the mind and nervous mat- 

 ter has ever been, and must continue to be, the deepest mystery in 

 physiology ; and they who study the laws of Nature, as ordinances 

 of God, will regard it as one of those secrets of His counsels 

 " which angels desire to look into."* The individual experience 

 of every thoughtful person, in addition to the inferences deducible 

 from revealed Truth, affords convincing evidence that the mind 

 can work apart from matter, and we have many proofs to shew 

 that the neglect of mental cultivation may lead to an impaired 

 state of cerebral nutrition ; or on the other hand, that diseased 

 action of the brain may injure or destroy the powers of the 

 mind. These are fundamental truths of vast importance to the 

 student of mental pathology as well as of physiology. It may 

 be readily understood that mental and physical development 

 should go hand in hand together, and mutually assist each other ; 

 but we are not, therefore, authorized to conclude that mental 

 action results from the physical working of the brain. The strings 

 of the harp, set in motion by a skilful performer, will produce 



* The admirable chapter in Bp. Butler's Analogy, " Of a Future Life," can- 

 not be too attentively studied in reference to this subject. 



