AND THE OCCULT SCIENCES.

...existing from eternity. If it is said that there was a time when that eternal Being had no knowledge, I reply that it would then have been impossible for there ever to have been any knowledge at all. It is as impossible for things that are completely devoid of knowledge—operating blindly and without any perception—to produce a conscious original: "knowing" being, as it is impossible for a triangle to make its own three angles larger than two right angles. Thus, by considering ourselves and what we unmistakably find in our own makeup, our reason leads us to the knowledge of this certain and evident truth: that there is an eternal, most powerful, and intelligent Being. Whether anyone chooses to call this Being "God" does not matter. The fact is evident; and from this idea, when properly considered, we can easily deduce all those other attributes we ought to assign to this eternal Being.

From what has been said, it is plain that we have a more certain knowledge of the existence of a God than of anything that our senses have not immediately revealed to us. In fact, I presume I may say that we know more certainly that there is a God than that there is anything else outside of us original: "without us," meaning external to our own minds. When I say "we know," I mean that such knowledge is within our reach; we cannot miss it if we will only apply our minds to it as we do to other inquiries.

Since it is unavoidable for all rational creatures to conclude that something has existed from eternity, let us next see what kind of thing that must be. There are only two types of beings in the world that man knows or can imagine: those that are purely material, without sense or perception; and conscious, perceiving beings, such as we find ourselves to be. For our present purpose, we shall call these two types thinking original: "cogitative" and non-thinking original: "incogitative" beings; these terms are more useful here than "material" and "immaterial."

If, then, there must be something eternal, it is very obvious to reason that it must necessarily be a thinking being. This is because it is as impossible to conceive that bare, non-thinking matter should ever produce a thinking, intelligent being, as it is that "nothing" should produce matter on its own. Let us suppose any portion of matter to be eternal; we shall find it unable to produce anything by itself. Let us suppose its parts are firmly at rest together; if there were no other being in the world, must it not remain so forever—a dead, inactive lump? Is it possible to imagine that it can add motion to itself or produce anything? Matter, then, by its own strength, cannot produce even motion in itself. Any motion it has must also be from eternity, or else be added to matter by some other being more powerful than matter. But even if we suppose motion is eternal too, non-thinking matter and motion could never produce thought. Knowledge would still be just as impossible for "nothing" to produce. Divide matter into as many minute parts as you like, and vary its shape and motion as much as you please, but it will still only affect other bodies...

+ Locke on the Human Understanding The author is citing Book IV, Chapter X of John Locke’s influential 1689 work, "An Essay Concerning Human Understanding," which argues that God's existence can be proven through reason.