5Q2 POPULAR SCIENCE MONTHLY. 



would search out the secrets of nature must humbly wait on experi- 

 ence, obedient to its slightest hint, is but partly true. This may be his 

 ordinary attitude; but now and again it happens that observation and 

 experiment are not treated as guides to be meekly followed, but as 

 witnesses to be broken down in cross-examination. Their plain mes- 

 sage is disbelieved, and the investigating judge does not pause until a 

 confession in harmony with his preconceived ideas has, if possible, 

 been wrung from their reluctant evidence. 



This proceeding needs neither explanation nor defense in those 

 cases where there is an apparent contradiction between the utterances 

 of experience in different connections. Such contradictions must of 

 course be reconciled, and science can not rest until the reconciliation 

 is effected. The difficulty really arises when experience apparently 

 says one thing and scientific instinct persists in saying another. Two 

 such cases I have already mentioned; others will easily be found by 

 those who care to seek. What is the origin of this instinct, and what 

 its value; whether it be a mere prejudice to be brushed aside, or a clue 

 which no wise man would disdain to follow, I can not now discuss. 

 For other questions there are, not new, yet raised in an acute form by 

 these most modern views of matter, on which I would ask your indul- 

 gent attention for yet a few moments. 



That these new views diverge violently from those suggested by 

 ordinary observation is plain enough. No scientific education is likely 

 to make us, in our unreflective moments, regard the solid earth on 

 which we stand, or the organized bodies with which our terrestrial fate 

 is so intimately bound up, as consisting wholly of electric monads very 

 sparsely scattered through the spaces which these fragments of matter 

 are, by a violent metaphor, described as ' occupying.' Not less plain 

 is it that an almost equal divergence is to be found between these new 

 theories and that modification of the common-sense view of matter with 

 which science has in the main been content to work. 



What was this modification of common sense? It is roughly indi- 

 cated by an old philosophic distinction drawn between what were called 

 the ' primary ' and the ' secondary ' qualities of matter. The primary 

 qualities, such as shape and mass, were supposed to possess an existence 

 quite independent of the observer; and so far the theory agreed with 

 common sense. The secondary qualities, on the other hand, such as 

 warmth and color, were thought to have no such independent existence ; 

 being, indeed, no more than the resultants due to the action of the 

 primary qualities on our organs of sense perception; — and here, no 

 doubt, common sense and theory parted company. 



You need not fear that I am going to drag you into the controver- 

 sies with which this theory is historically connected. They have left 

 abiding traces on more than one system of philosophy. They are not 



