PHYSICS OF THE BRAIN. 
423 
substance, each independent, free, and capable of motion when 
the whole mass is charged with force. The brain, in fact, is a 
world within of the world without, a camera of all from the 
w T orld without that it has received in the course of its waking 
life. Until recently the idea of such a physical microcosm could 
not have been conceived ; now it comes forward strengthened by 
physical truths of human invention so called. I hold a piece of 
transparent glass in my hand and see nothing upon it. Nay, 
says my friend the micro-photographer, look again. Still no- 
thing there? No! Then he slides the glass under his lenses 
and adjusts, and repeats, “ Look again.” I obey, and lo ! before 
me on an infinitesimal space of matter is the Pater Noster, as 
legible as it used to be in an old church I well remember, 
where it covered half a wall, and, with the ten commandments 
to balance it, enframed the Lion and the Unicorn, and Greorgius 
Eex, and the Grarter, like a holy family. 
When we see v 7 hat the micro-photographer can thus do in 
putting physical impressions on what seem infinitesimal points of 
matter, and when we know that there is no assignable limit to his 
art, it is no crude inference that in the vast surface of the grey 
matter of the brain, in those cerebral lobes of which I have 
spoken, myriads of points of matter are thus impressed — points 
of matter floating in that eighty-four per cent, of water of 
which the brain is made up. I call up to remembrance a ridge 
of hills which were often before me in childhood. I see them 
in all the distinctness of that time, their height, their breadth, 
their length, their divisions, the structures upon them, all their 
belongings. Why do I see them ? Because they are actualities 
still in my brain, imprints on points of matter there. But 
twenty yehrs elapse, and I look on those hills again, and they 
are and yet are not what they were. They seem to my present 
view smaller, that is certain ; and one of them was barren, 
and now it is cultivated; and one had a mill on its sum- 
mit, and the mill is gone ; and one had two or three trees on its 
side, which in the distance looked like the flint and steel of an 
old-fashioned gun, but now in place of those trees is a copse. 
These are not the hills, in fact, which I have carried so many 
years, for now as I take them in once more my capacity for 
taking has changed and the hills have changed. I must have 
therefore a new picture altogether ; and from this time forward 
I must carry two pictures of those hills, the child’s picture and 
the man’s picture ; for the old is not put out by the new, nor 
the new by the old. 
Physical points of brain for physical impressions are then 
essential ; but to reveal their impressions they must have force 
and condition for motion. Let us remove that force, abstract 
it, as it comes to the part, by cold, or crush it out b} 7 firm 
mechanical pressure, or cut it off at its source by putting out 
