336 THE POPULAR SCIENCE MONTHLY. 



be proved nor disproved, are the conventional definitions of matter, 

 and accepted distinctions between matter and mind, or other forms of 

 force. 



The qualities that for ages have been attributed to matter, as iner- 

 tia and extension, apply correctly enough to that limited portion and 

 form of matter that the senses can appreciate ; but, as has been shown, 

 all but an infinitesimal portion of Nature is permanently sealed against 

 the senses. What warrant have we, beyond undemonstrable proba- 

 bility, that the attributes of that portion of matter that can be reached 

 by the senses belong also to all that portion of which the senses can 

 directly teach us nothing ? How do we know that the familiar forces, 

 as light, heat, electricity, and gravity, may not be as truly matter as 

 the Atlantic Ocean or Mont Blanc ? 



Standing on the outermost verge of conceivable science, and casting 

 the line of probability into the dark unknown, as far as it is possible 

 for human weakness, will it, can it reach any more rational gener- 

 alization than this, that all Nature is unity? Whether the common 

 axioms of human reasoning such as the whole is greater than a part, 

 every effect must have an adequate cause, every thought must have a 

 thinker, a thing cannot be and not be at the same time do or do not 

 apply to the supernatural, the mind of man is powerless to determine. 



Under this head come all conceivable questions relating to the exist- 

 ence and nature of other universes than ours. 



A question of great interest, or would be if it could be answered, is 

 that of spontaneous generation, which from the limitations of the human 

 senses can neither be proved nor disproved. 



How is it possible for the human faculties to determine what degree 

 of heat any supposable living substance, or intermediate substance be- 

 tween living and non-living, beyond the reach of the microscope, may 

 bear? There are gradations of endurance in living things that are 

 accessible to the senses. What are the limits of this gradation through 

 the realm of the infinitely little? If, therefore, all experts in this 

 branch of inquiry should agree that fluids subjected to a very much 

 higher degree of heat than has yet been employed in experiments of this 

 kind shall yet, when every conceivable precaution against sources of 

 error has been taken, develop some of the lower forms of life, the ques- 

 tion of spontaneous generation would still be an open one. 



The present and prospective state of the spontaneous generation 

 question is, then, as follows : 



1. Science has no absolute deduction for or against it. 



2. It is impossible by present deduction or by conceivable induction 

 to either positively prove or disprove it. 



Discussions on the subject, like that between Tyndall and Bastian, 

 are on both sides unscientific, as they are unsatisfactory, and would not 

 be indulged in by those who have correct ideas of the limitations of the 

 senses. 



