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 ITSELF, 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 showing that the parts of sensible bodies are held together by the pressure of other external insensible bodies, reaches not the parts of the aether itself; 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 itself: 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.
24.

Not explained by an ambient fluid.
But, in truth, the pressure of any ambient fluid, how great soever, can be no intelligible cause of the cohesion of the solid parts of matter.
For, though such a pressure may hinder the avulsion of two polished superficies, one from another, in a line perpendicular to them, as in the experiment of two polished marbles; yet it can never in the least hinder the separation by a motion, in a line parallel to those surfaces.
Because the ambient fluid, having a full liberty to succeed in each point of space, deserted by a lateral motion, resists such a motion of bodies, so joined, no more than it would resist the motion of that body were it on all sides environed by that fluid, and touched no other body; and therefore, if there were no other cause of cohesion, all parts of bodies must be easily separable by such a lateral sliding motion.

For if the pressure of the aether be the adequate cause of cohesion, wherever that cause operates not, there can be no cohesion.

And since it cannot operate against a lateral separation, (as has been shown,) therefore in every imaginary plane, intersecting any mass of matter, there could be no more cohesion than of two polished surfaces, which will always, notwithstanding any imaginable pressure of a fluid, easily slide one from another.