— 308 —
Cohesion of solid parts in Body, as hard to be conceived as Thinking in a Soul.       §23. If any one says, he knows not what ’tis thinks in him; he
means he knows not what the substance is of that thinking thing:
No more, say I, knows he what the substance is of that solid thing.
Farther, if he says he knows not how he thinks; I answer, Neither
knows he how he is extended; how the solid parts of Body are
united, or cohere together to make Extension. For though the
pressure of the Particles of Air, may account for the cohesion of
several parts of Matter, that are grosser than the Particles of Air, and
have Pores less than the Corpuscles of Air; yet the weight, or
pressure of the Air, will not explain, nor can be a cause of the
coherence of the Particles of Air themselves. And if the pressure of
the AEther, or any subtiler Matter than the Air, may unite, and hold
fast together the parts of a Particle of Air, as well as other Bodies;
yet it cannot make Bonds for it self, and hold together the parts,
that make up every the least corpuscle of that materia subtilis. So that
that Hypothesis, how ingeniously soever explained, by shewing, that
the parts of sensible Bodies are held together, by the pressure of
other external insensible Bodies, reaches not the parts of the AEther
it self, and by how much the more evident it proves, that the parts
of other Bodies are held together, by the external pressure of the
AEther, and can have no other conceivable cause of their cohesion
and union, by so much the more it leaves us in the dark, concerning
the cohesion of the parts of the Corpuscles of the AEther it self:
which we can neither conceive without parts, they being Bodies,
and divisible; nor yet how their parts cohere, they wanting that
cause of cohesion, which is given of the cohesion of the parts of all
other Bodies.
Locke Hum II, 23, §23, p. 308