336 THE POPULAR SCIENCE MONTHLY. 



investigations into that border-territory of Nature where animal and 

 vegetable life touch, we meet with so-called monads the Heteromita, 

 for example which may be referred with equal justice to either king- 

 dom ; there are organisms which we think vegetable, having charac- 

 ters which we call animal, and organisms which we call animal, hav- 

 ing characters which we think vegetable ; there is, in truth, no line 

 of demarkation, but instead an insensible series of gradations, and no 

 man can say where the one kingdom ends and the other begins. In 

 like manner, notwithstanding the seemingly gross and palpable dis- 

 tinction between living and dead matter, any one who sets himself to 

 work to find out where life begins will be hard put to it to draw a 

 line of separation, and more hard put to it when called upon to make 

 good his division. Man himself, much as he makes of himself, is not 

 separated from the rest of Nature by an impassable gulf; he modifies 

 Nature largely, it is true, but the art by which he does that is Nature ; 

 he is a part of the order thereof the latest product of the evolution 

 which went on for countless ages before he appeared upon earth, 

 which is going on now in his progress, his knowledge and his moral 

 feelings being agencies in the process, and which, for anything we 

 know, will go on for countless ages after the earth, which he has 

 ceased to replenish and subdue, has fallen into the condition in which 

 the moon now is, and rolls on its solitary way through space, a cold 

 and desert globe, the tomb of all human aspirations, sorrows, sins, 

 and achievements. In making use, then, of the arbitrary divisions 

 of our sciences, we ought never to lose hold of the actual unity and 

 continuity of Nature ; never to overlook the fact that there is not a 

 single truth in any science which has not its essential relations with 

 the truths of all sciences ; never to forget that the least things and 

 the greatest are indissolubly bound together as equally essential ele- 

 ments of the intimately conuected and mysterious whole which we call 

 the universe. It may seem a fanciful saying, but there is a truth in it, 

 that you cannot utter an exclamation, strike a note on a piano, move 

 a grain of sand from its place, without affecting the entire universe. 



Now the systematic training of the mind in conformity with the 

 order of Nature, through patient observation and careful induction, 

 the knowledge of Nature which is got by becoming, as Bacon says, 

 her servant and interpreter, is a tedious business. Men, therefore, 

 have gladly shirked it ; they have found it much easier to attribute 

 phenomena to some metaphysical entity which they have created out 

 of a mental abstraction, or to invoke a supernatural cause to account 

 for them, than to find out the explanation. In consequence of this 

 habit of mind, which has had large operation in the past, a body of 

 doctrine has grown up which, having had its day, is now fast becoming 

 effete, but which men will not willingly part with doctrine com- 

 parable, if I may use a physiological comparison, with those organs 

 which, like the thymus gland, have their uses at a certain stage of 



