224 FRAGMENTS OP SCIENCE. 
her secrets and the patient mastery of her laws. This not 
only enables ns to protect ourselves from the hostile action 
of natural forces, but makes them our slaves. By the study 
of Physics we have indeed opened to us treasuries of power 
of which antiquity never dreamed. But while we lord it 
over Matter, we have thereby become better acquainted 
with the laws of Mind; for to the mental philosopher the 
study of Physics furnishes a screen against which the human 
spirit projects its own image, and thus becomes capable of 
self-inspection. 
Thus, then, as a means of intellectual culture, the study 
of Physics exercises and sharpens observation : it brings the 
most exhaustive logic into play: it compares, abstracts, 
and generalizes, and provides a mental scenery appropriate 
to these processes. The strictest precision of thought is 
everywhere enforced, and prudence, foresight, and sagac- 
ity are demanded. By its appeals to experiment, it con- 
tinually checks itself, and thus walks on a foundation of 
facts. Hence the exercise it invokes does not end in a 
mere game of intellectual gymnastics, such as the ancients 
delighted in, but tends to the mastery of Nature. This 
gradual conquest of the external world, and the conscious- 
ness of augmented strength which accompanies it, render 
the study of Physics as delightful as it is important. 
With regard to the effect on the imagination, certain it 
is that the cool results of physical induction furnish con- 
ceptions which transcend the most daring flights of that 
faculty. Take for example the idea of an all-pervading 
ether which transmits a tingle, so to speak, to the finger 
ends of the universe every time a street lamp is lighted. 
The invisible billows of this ether can be measured with the 
same ease and certainty as that with which an engineer meas- 
ures a base and two angles, and from these finds the distance 
across the Thames. Now it is to be confessed that there 
may be just as little poetry in the measurement of an ethe- 
real undulation as in that of the river; for the intellect, 
during the acts of measurement and calculation, destroys 
those notions of size which appeal to the poetic sense. It is 
a mistake to suppose, with Dr. Young, that 
An undevout astronomer is mad; 
there being no necessary connection between a devout 
state of mind and the observations and calculations of a 
