744 SCIENTIFIC THOUGHT. 



noted as a connection, a bond of union, between those 

 two great realms of systematic thought which, for the 

 sake of convenience, I have kept apart in this historical 

 survey. 



There are other features in the scientific thought 

 of the period, as it has become known to us, which 

 naturally lead up to a different treatment from that 

 which is peculiar to science. In almost every instance, 

 in following up the various aspects of scientific thought, 

 I have had to show how they have brought us to 

 problems which cannot be solved by the means which 

 we call scientific or exact ; and in many instances I 

 have shown how the foremost scientific thinkers them- 

 selves have been led up to inquiries which they have 

 variously termed philosophical, metaphysical, logical, or 

 psychological. Such has notably been the case with 

 the ultimate conceptions of the atomic theory, of the 

 doctrine of energy, and, still more, with the concep- 

 tions which underlie the scientific treatment of the 

 phenomena of life and consciousness. The further we 

 have advanced from the simple mechanical conceptions 

 of motion and inertia or mass, into the phenomena 

 of the actual world of natural objects which exhibit 

 order, development, purpose, and consciousness, the 

 more we have been obliged to make use of terms 

 not capable of being defined by the simple categories of 

 exact or mathematical thought ; and with whatever 

 zeal some of the foremost thinkers have in the course 

 of the century attempted to express these more indefinite 

 conceptions in terms of mechanical science, they have 

 only partially succeeded, and have certainly failed in 



