14 NATURE AND LIFE. 
certain primal energies come into union to give rise, 
through a thousand successive complications, to phencm- 
ena and to bodies, what they really produce is not the ap- 
pearance of extension, which is the mere shadow of reality, 
but it is that collection of varied and diverse activities 
which enable us to describe and define phenomena and 
bodies. 
It is no longer a subject of doubt, in the minds of sa- 
vants who have got beyond experimentation, that exten- 
sion is an image and a show rather than an essential con- 
stituent property of bodies. The extension of bodies is a 
phenomenon which takes its rise in the collision of force 
with our minds. - Charles de Rémusat, so long ago as 1842, 
gave an original and remarkable demonstration of this. 
He maintains that force is the cause of extension, meaning 
by that that the sensation of extension is a modification 
of our sensibility, occasioned by forces analogous to those 
which produce sensations of a more complex kind. When. 
you experience an electric shock, you are struck. Percus- 
sion is the sensation of contact,in other words, of impul- 
sion by something that has extension. Now, in this in- 
stance, Rémusat says, the cause of percussion, electricity, 
has no extension. Therefore, he adds, either electricity is 
nothing, or else it is a force which affects us in a way that 
may be compared to the effect of extension. So that a 
force, wanting the usual appearances of extension, may 
produce the same effects on us that a solid body in motion 
does. Within afew yearsa profound metaphysician, Magy, 
has pointed out by new arguments that corporeal exten- 
sion is merely a show which springs from the internal reac- 
tion of the soul against the impression made on the sen- 
sorium, and which the soul translates to outward bodies, 
by a law analogous to that which makes it localize in the 
separate organs of sense the impression which it has ney- 
ertheless perceived only in the brain. Hach sensation of 
7. 
