n _all_ cases the measure of the force--proceeds to deposit a third
stratum upon the second:--and so on, until these concentric strata,
growing gradually less and less, come down at length to the central
point; and the diffusive matter, simultaneously with the diffusive
force, is exhausted.

We have now the sphere filled, through means of irradiation, with atoms
equably diffused. The two necessary conditions--those of irradiation and
of equable diffusion--are satisfied; and by the _sole_ process in which
the possibility of their simultaneous satisfaction is conceivable. For
this reason, I confidently expect to find, lurking in the present
condition of the atoms as distributed throughout the sphere, the secret
of which I am in search--the all-important principle of the _modus
operandi_ of the Newtonian law. Let us examine, then, the actual
condition of the atoms.

They lie in a series of concentric strata. They are equably diffused
throughout the sphere. They have been irradiated into these states.

The atoms being _equably_ distributed, the greater the superficial
extent of any of these concentric strata, or spheres, the more atoms
will lie upon it. In other words, the number of atoms lying upon the
surface of any one of the concentric spheres, is directly proportional
with the extent of that surface.

_But, in any series of concentric spheres, the surfaces are directly
proportional with the squares of the distances from the centre._[2]

[2] Succinctly--The surfaces of spheres are as the squares of
their radii.

Therefore the number of atoms in any stratum is directly proportional
with the square of that stratum's distance from the centre.

But the number of atoms in any stratum is the measure of the force which
emitted that stratum--that is to say, is _directly proportional_ with the
force.

Therefore the force which irradiated any stratum is directly
proportional with the square of that stratum's distance from the
centre:--or, generally,

_The force of the irradiation has been directly proportional with the
squares of the distances._

Now, Reaction, as far as we know anything of it, is Action conversed.
The _general_ principle of Gravity being, in the first place, understood
as the reaction of an act--as the expression of a desire on the part of
Matter, while existing in a state of diffusion, to return into the Unity
whence it was diffused; and, in the second place, the mind being called
upon to d