VIE CROW AND EVOLUTION. 275 



equilibrium, which there is an immediate effort to restore. The effort, 

 incessantly defeated — for the waves continue to pour in — is incessantly 

 renewed; in the molecular struggle, matter is gathered from the soil 

 and from the atmosphere, and built, in obedience to the forces which 

 guide the molecules, into the special form of the tree. In a general way, 

 therefore, the life of the tree might be defined as an unceasing effort 

 to restore a disturbed equilibrium. In the building of crystals, Nature 

 makes her first structural effort ; we have here the earliest groping of 

 the so-called " vital force," and the manifestations of this force in plants 

 and animals, though, as already stated, indefinitely more complex, are 

 to be regai'ded of the same mechanical quality as those concerned in 

 the building of the crystal. 



Consider the cycle of operations by which the seed produces the 

 plant, the plant the flower, the flower again the seed, the causal line 

 returning with the fidelity of a planetary orbit to its original point of 

 departure. Who or Avhat planned this molecular rhythm ? We do not 

 know — science fails even to inform us whether it was ever " planned " 

 at all. Yonder butterfly has a spot of orange on its wing ; and if we 

 look at a drawing made a century ago, of one of the ancestors of that 

 butterfly, we probably find the self-same spot upon the wing. For a 

 century the molecules have described their cycles. Butterflies have 

 been begotten, have been born, and have died ; still we find the molecu- 

 lar architecture reproduced. Who or what determined this persistency 

 of recurrence ? We do not know ; but we stand within our intellectual 

 range when we say that there is probably nothing in that wing which 

 may not yet find its Newton to prove that the principles involved in its 

 construction are qualitatively the same as those brought into play in the 

 formation of the solar system. We may even take a step further, and 

 afiirm that the brain of man — the organ of his reason and his sense — 

 without which he can neither think nor feel — is also an assemblage of 

 molecules, acting and reacting according to law. Here, however, the 

 methods pursued in mechanical science come to an end ; and if asked 

 to deduce from the physical interaction of the brain-molecules the least 

 of the phenomena of sensation or thought, we must acknowledge our 

 helplessness. The association of both with the matter of the brain may 

 be as certain as the association of light with the rising of the sun. But 

 whereas in the latter case we have unbroken mechanical connection 

 between the sun and our organs, in the former case logical continuity 

 disappears. Between molecular mechanics and consciousness is inter- 

 posed a fissure, over which the ladder of physical reasoning is incom- 

 petent to carry us. We must, therefore, accept the observed associa- 

 tion as an empirical fact, without being able to bring it under the yoke 

 of a priori deduction. 



Such were the ponderings which ran habitually through my mind in 

 the days of my scientific youth. They illustrate two things : a determi- 



