THE UNITY OF SCIENCE 29 



in an ascending scale, according to the comparative complex- 

 ity, intricacy and elusiveness of the phenomena with which, 

 they deal. In such an arrangement, we are wont to place 

 psychology above biology, biology above chemistry, chemistry 

 above physics ; and at the bottom of physics we place mechan- 

 ics probably, in the last analysis, the mechanics of the mol- 

 ecule or the atom or the electron. And, as has been intimated,, 

 a thorough unification of science, in the sense defined, would 

 mean the 'reduction' of each of these sciences to the one next 

 below it in the series, until all were finally 'reduced' to me- 

 chanics: they would all finally appear as necessary conse- 

 quences of a single, brief, simple, undeviating set of laws des- 

 cribing the relative motion of the ultimate homogeneous units of 

 matter. These laws would hold good of the action of a given 

 unit of matter at all moments of its history : at the time when 

 it was part of a nebular gas ; or while it was part of a rock 

 seemingly motionless for ages; or when it was part of a 

 developing cell in some living animal ; or when it was part of 

 the brain of a Plato conceiving the Symposium, or of the hand 

 of a Socrates put forth to take the hemlock. Thus from these 

 laws together with the number and the antecedent positions 

 of all the units together would follow equally every motion 

 that any portion of matter makes at any time; by one who 

 knew them, all phenomena could, as we have already seen, be 

 perfectly deduced, and predicted beforehand even the actions 

 of human bodies. For, of course, the march of a martyr to 

 his death and the pressure of a murderer's finger upon a 

 trigger are no less motions of matter than the fall of a rock 

 or the circling of a star. Such a unification of scientific laws, 

 when it thus embraces in its scope the physical phenomena 

 which we are prone to ascribe to the agency of human thoughts 

 and feelings, obviously just because it is and must be a uni- 

 fication downward leaves what is called consciousness a 

 rather superfluous figure upon the cosmic scene. And that it 

 is so has, as you know, been maintained by many who have 

 made their own what they conceive to be the general teaching 



