92 THE POPULAR SCIENCE MONTHLY 



quaintly said, " things of the same kind go through the same formali- 

 ties " — celebrate, as it were, the same ceremonial rites. 



This formal activity which operates throughout a series of changes 

 and holds them to a single course; that subordinates their aimless flux 

 to its own perfect manifestation ; which, leaping the boundaries of space 

 and time, keeps individuals in spite of their being distant in space and 

 remote in time to a uniform type of structure and function : this prin- 

 ciple seemed to give insight into the very nature of reality itself. To it 

 Aristotle gave the name, elSos. This term the scholastics translated 

 as species. 



The force of this term was deepened by its application to everything 

 in the universe that observes order in flux and manifests constancy 

 through change. From the casual drift of daily weather, through the 

 uneven recurrence of seasons and unequal return of seed time and har- 

 vest, up to the majestic sweep of the heavens — the image of eternity in 

 time — and from this to the unchanging pure and contemplative intelli- 

 gence beyond nature lies one unbroken fulfilment of ends. Nature, as 

 a whole, is a progressive realization of purpose strictly comparable to 

 the realization of purpose in any single plant or animal. 



The conception of eTSos, species, the fixed form and final cause, was 

 the central principle of knowledge as well as of nature. Upon it 

 rested the logic of science. Change as change is mere flux and lapse; 

 it insults intelligence. Genuinely to know is to grasp a permanent 

 end that realizes itself through changes, holding them thereby within 

 the metes and bounds of fixed truth. Completely to know is to re- 

 late all special forms to their one single end and good: pure contem- 

 plative intelligence. Since, however, the scene of nature which directly 

 confronts us is in change, nature as directly and practically experienced 

 can not satisfy the conditions of knowledge. Human experience is also 

 in flux, and hence the instrumentalities of sense-perception and of in- 

 ference based upon observation are condemned in advance. Science is 

 compelled to aim at realities lying behind and beyond the processes of 

 nature, and to carry on its search for these realities by means of 

 rational forms transcending ordinary modes of perception and inference. 



There are, indeed, but two alternative courses. We must either 

 find the appropriate objects and organs of knowledge in the mutual 

 interactions of changing things; or else, to escape the infection of 

 change, we must seek them in some transcendent and supernal region. 

 The human mind, deliberately as it were, exhausted the logic of the 

 changeless, the final and the transcendent, before it essayed adventure 

 on the pathless wastes of generation and transformation. We dispose 

 all too easily of the efforts of the schoolmen to interpret nature and 

 mind in terms of real essences, hidden forms and occult faculties, for- 

 getful of the seriousness and dignity of the ideas that lay behind. We 



