This system certainly embraces great absurdities, and greater to my mind than those it would fain avoid. We conceive clearly that matter is divisible, and capable of motion; but we do not conceive that it is capable of thought, nor that thought can consist of a certain configuration or a certain motion of matter. And even could thought depend on an arrangement, or on a certain subtility, or on a certain motion of matter, as soon as that arrangement should be disturbed, or the motion interrupted, or this heap of subtile matter dispersed, thought would cease to be produced, and consequently that which constitutes man, or the reasoning animal, would no longer subsist; thus all the economy of our religion, all our hopes of a future life, all our fears of eternal punishment would vanish; even the principles of our philosophy would be overthrown.
God forbid that we should wish to set bounds to the almighty power of God; but that all-powerful Being having given us as a rule of our knowledge the clearness of the ideas which we form of everything, and not being permitted to affirm that which we know but indistinctly, it follows that we ought not to assert that thought can be attributed to matter. If the thing were known to us through revelation, and taught by the authority of the Scriptures, then we might impose silence on human reason, and make captive our judgment in obedience to faith; but it is owned that the thing is not at all revealed; neither is it demonstrated, either by its cause, or by its effects. It must, then, be considered as a simple system, invented to do away certain difficulties which result from the opinion opposed to it.
If the difficulty of explaining how the soul acts upon our bodies appears so great, how can we comprehend that the soul itself should be material and extended? In the latter case will it act upon itself, and give itself the impulsion to think, or will this movement or impulsion be thought itself, or will it produce thought? Will this thinking matter think on always, or only at times; and when it has ceased to think, who will make it think anew? Will it be God, will it be itself? Can so simple an agent as the soul act upon itself, and reproduce it in some sort by thinking, after it has ceased to think?