G38 FRAGMENTS OF SCIENCE. 
thought, I acknowledge my helplessness. The association 
of both with the matter of the brain may be as certain as 
the association of light with the rising of the sun. Bat 
whereas in the latter case we have unbroken mechanical 
connection between the sun and our organs, in the former 
case logical continuity disappears. Between molecular 
mechanics and consciousness is interposed a fissure over 
which the ladder of physical reasoning is incompetent to 
carry us. We must, therefore, accept the observed associ- 
ation as an empirical fact, without being able to bring it 
under the yoke of a priori deduction. 
Such were the ponderings which ran habitually through 
my mind in the days of my scientific youth. They 
Illustrate two things-Ai determination to push physical 
considerations to their utmost legitimate limit; and an 
acknowledgment that physical considerations do not lead 
to the final explanation of all that we feel and know. 
This acknowledgment, be it said in passing, was by no means 
made with the view of providing room for the play of con- 
siderations other than physical. The same intellectual 
duality, if I may use the phrase, manifests itself in the 
following extract from an article entitled " Physics and 
Metaphysics," published in the Saturday Review for 
August 4, 1860: 
" The philosophy of the future will assuredly take more 
account than that of the past of the dependence of thought 
and feeling on physical processes; and it may be that the 
qualities of the mind will be studied through organic com- 
binations as we now study the character of a force through 
the affections of ordinary matter. We believe that every 
thought and every feeling has its definite mechanical 
correlative that it is accompanied by a certain breaking 
up and rernarshaling of tne atoms of the brain. This 
latter process is purely physical; and were the faculties we 
now possess sufficiently expanded, without the creation of 
any new faculty, it would doubtless be within the range of 
our augmented powers to infer from the molecular state of 
the brain the character of the thought acting on it, and, 
conversely, to infer from the thought the exact molecular 
condition of the brain. We do not say and this, as will 
be seen, is all-important that the inference here referred 
to would be an a priori one. But by observing, with the 
