5 8 THE POPULAR SCIENCE MONTHLY. 



process of arriving at fair judgments is both laborious and painful. 

 Instead, however, of assuming certainty because it is desirable, we 

 would endeavor to earn it, by recognizing it as every man's duty and 

 privilege to add to truth, in the justness, completeness, and clearness 

 of his knowledge of it. And, since the scope of the unknown is infi- 

 nite, the incitement to the fulfillment of this duty is full of hope and 

 promise. Science, unlike dogma, does not point to fields harvested 

 and gleaned long ago, but to continents awaiting their Columbus to 

 pressing problems of individual, social, and political life demanding 

 solutions by thoughtful men. And, in the fields of scientific investiga- 

 tion, we can see how every newly ascertained fact and law extends the 

 horizon of Nature, adds to the area of unexplored territory, thereby 

 stimulating the student to achievement therein. In researches re- 

 specting mind and brain, and their relations, in probing conscious- 

 ness to its depths, and in the results which may follow the inquiry as 

 to whether the intellect does or does not come into direct contact with 

 external Nature, some of the ablest thinkers of our time place hope 

 of more light on the chief problems of life. Our conception, then, 

 of knowledge leads us back to the early similitude which likened 

 it to a tree. Knowledge does not increase, like a honey-comb, cell 

 simply added to cell, but, like an oak, whose every year of growth 

 implies not addition merely, but vital transformation of structure. 

 Nothing is fixed but the axis from which the branches and boughs 

 spread out, as if they felt they had all the universe for their expan- 

 sion. A stripling oak of a few seasons' growth is beautiful enough 

 in its way ; but would it be wise or useful to uproot it, shelve it 

 in a museum, and declare it to represent a finality as to oak- possi- 

 bilities ? 



The idea of knowledge which I have sought to express makes 

 clear the grounds whereon thought and discussion ask for full liberty. 

 As men differing in natural ability, temperament, education, and 

 stand-point, strive to attain views of truth, their results must inevita- 

 bly vary. "Recognition of difference of view" we would, then, sub- 

 stitute for the offensive term " toleration of dissent," which latter 

 phrase, from one who holds that he possesses finality, simply means 

 the permission of known error, which he may be unwilling or un- 

 able to punish. And the differences of view which men of opposite 

 temperaments and tendencies may entertain are often mutually com- 

 pleting, and become indued in a master-mind with stereoscopic relief 

 and unity. Let me cite an example of this : Two schools of thought 

 endeavored to explain conscience on different principles. The one 

 held it to arise from an innate moral sense, the other from the results 

 of experience. The philosophy of evolution includes in its explana- 

 tion both series of facts from which these two schools argued. It 

 shows how ancestral experiences of right and wrong conduct become 

 organized in the race, and are transmitted as moral tendencies to off- 



