We all know from experience that an acorn develops into an oak tree. It’s as if the mature oak shapes or molds the acorn’s growing activity, influencing the acorn to act in one way rather than some other way—say, developing into a banana tree. And the fact that an acorn, unimpeded and under the ideal circumstances, is settled on developing into an oak tree—rather than a banana tree—is not something we impose upon the acorn. We only discover it. It is intrinsic to the acorn; it belongs to what an acorn is to have that goal.
But how can the oak shape or mold an acorn, giving it a specific direction, if it doesn’t yet exist?
To answer this question, we can move a little closer to “home.” Consider the college student, and how the hope of graduating influences or shapes his activity. It’s the end goal—the college degree—that influences the student to take classes and study hard.
Before the student sets off to college, the college degree he’ll (hopefully) eventually attain doesn’t exist in reality. But it does exist in his mind. He thinks about a college degree and says, “That’s what I want to achieve. And here are the means to achieve it.”
This “existence in the mind”—what some philosophers call mental existence—influences and governs the student’s activity, both in the beginning and as he continues pursuing his goal. In fact, that’s the only way an end or goal that doesn’t exist in the real world can influence a thing’s activity.
This makes perfect sense to us when we’re talking about a college student seeking to earn a degree, because a college student is a being with intellect and free will. But a problem arises when we consider things that lack intelligence, like an acorn.
Unlike the college student, the acorn has no mind to think about its specific effect of producing a mature oak tree. So the question becomes, “What determines the activity of an acorn to become a mature oak?”
One answer is the substantial form of the acorn—that principle that establishes the acorn as the kind of thing that it is. The specific end or goal of the acorn (being a mature oak) pre-exists in the acorn’s form by way of potency and is actualized as it naturally grows. So the goal-directedness of the acorn’s activity toward a mature oak is intrinsic to, or embedded within the nature of, the acorn.
Now, although the substantial form accounts for this goal-directed activity to some degree, it ultimately falls short of a complete explanation. We’re still left with the question, “But what makes the form of the acorn have an activity that’s specifically directed toward being a mature oak rather than a banana tree?”
We know that there must be something to account for such determinate activity. If there weren’t, then there would be nothing to account for the reliable correlation between the form of the acorn and the state of being a mature oak. The acorn really could become a banana tree, or any other kind. Therefore, there must be something that accounts for the determinate activity that proceeds from the form of the acorn, something that combines the form with the activity that has as its end or goal a mature oak tree. And whatever this something is, the acorn in and of itself cannot account for it.
But this just raises another question, which brings us back full circle: “How can the state of a mature oak tree determine anything the acorn does when the mature oak doesn’t exist?”
After all, if the mature oak tree didn’t exist in anyway whatsoever, then the acorn and its activity would be related to nothing, which can’t be. Therefore, the oak must exist in some way. And the only way it can possibly exist, other than in reality, is in a mind of some sort that has knowledge of it.
Now, the knowledge of the end state of a mature oak tree is not merely sensate knowledge (like how a dog has some degree of knowledge of the goal of attaining food by running toward its bowl). Rather, we’re talking about intelligence, which is knowledge proper to rational beings. The reason is that the combining of the form of an oak in its acorn stage with its mature stage of an oak tree involves a grasping or an awareness of the form or nature of the oak and its end state of flourishing.
To grasp such a form in this way is just what it means to have intelligence. Therefore, there must exist an agent with intelligence outside the acorn that can think about the end or goal of a mature oak tree and govern, order, or direct the acorn to produce its specific effect—to achieve its end.
And this governance, or directing activity, would apply not just when the acorn begins to act to produce such an effect, but at every moment the acorn’s activity is moving toward producing its effect. For if the form of the acorn can’t account for the intelligence needed to direct its activity to its specific end or goal in the beginning, then its form won’t be able to account for the intelligence needed to direct its activity to its specific end or goal at any moment its activity is producing its specific effects.
Maybe someone could argue that this intelligent governor is the gardener who plants and tends the acorn. But that can’t be, since, as we said above, we humans merely discover this inherent tendency of the acorn to grow into a mature oak. The gardener can only guide the growth process from the outside.
Therefore, there must be some intelligent governor that has direct causal influence on the acorn’s natural powers—indeed on the acorn’s being—guiding it “from the inside,” as it were. And if this governor doesn’t direct the acorn to produce its effect by virtue of his own essence, but rather does so through another, then our inquiry for a satisfactory explanation must continue until we arrive at an ultimate intelligent governor—a governor who directs the acorn to produce its effect by virtue of his own essence, and not through another. Such an ultimate intelligent governor is what we can call God.
This line of reasoning isn’t new, but it certainly is powerful. In fact, we’ve just gone through the fifth of St. Thomas Aquinas’s Five Ways to prove God’s existence. From an acorn to God—who would have thought?