How to See the Invisible: Bonaventure's Universe of Signs

Imagine you’re walking through a forest. You notice a footprint in the mud. You don’t need to see the animal that made it to know something was here—the print itself points to something beyond itself. Now imagine that everything in the entire universe is like that footprint. Every rock, every star, every thought you have, every time you know something for certain—all of it is a sign pointing toward something invisible that made it all possible.

That’s the strange and beautiful idea at the heart of Bonaventure’s philosophy.

Bonaventure was a 13th-century monk who thought deeply about one big question: How can we know that God exists, and what is God like? But he didn’t just want an answer you could memorize. He wanted to show that the whole world is filled with clues—and that you’re already using the most important ones without realizing it.

A World Full of Footprints

Bonaventure believed that everything that exists is like a sign. He had a whole vocabulary for this. Some things are just “shadows” of God—vague hints, like seeing a blurry shape in the dark. Other things are “vestiges” or footprints—clearer signs that show you something about where they came from. A tree, for example, shows you something about its creator: it exists (that points to power), it has a particular nature (that points to wisdom), and it’s good for something (that points to goodness).

But here’s where it gets interesting. Humans aren’t just footprints. We’re “images” of God. What does that mean? Think about what makes you different from a rock or a tree. You can think, you can choose, you can love. Your mind has three basic powers: memory, understanding, and will. Bonaventure noticed that these three work together in a way that strangely mirrors what Christians believe about God being three persons in one. Your memory holds onto things, your understanding makes sense of them, and your will reaches out to act on what you understand. They’re three different things, but they’re all you.

This trippy idea—that your own mind is a kind of mirror reflecting something infinite—is where Bonaventure’s philosophy really takes off.

The Three Paths to God

Bonaventure thought there were three main ways to know that God exists. He didn’t think you had to pick just one. He used all three, and he ranked them: one makes you “certain,” one makes you “more certain,” and one shows that God’s existence is the most obvious truth there is—if you know how to look.

Path 1: The Argument from Inside Your Head (Certain)

This one starts with something you experience all the time: knowing something for sure.

Think about a math fact: 2 + 2 = 4. You don’t just believe this—you know it. Could it ever be false? No. Is it true only in your head? No—if someone else adds 2 and 2, they get 4 too. This truth feels solid and unchanging in a way that most things in life don’t. Your opinion about the best pizza topping can change. Your friendship with someone can change. But 2 + 2 = 4 doesn’t change.

Bonaventure asked: where does that certainty come from? Not from your senses—your senses can be wrong (optical illusions, mirages). Not from your brain alone—your brain makes mistakes all the time. He argued that for you to grasp something absolutely certain and unchanging, your mind must be connected to something that is itself absolutely certain and unchanging. That something, he said, is God.

This doesn’t mean you’re thinking about God every time you do math. It’s more like this: when you flip a light switch, the light comes on because there’s a whole power grid behind it that you’re not thinking about. In the same way, when your mind grasps a certain truth, it’s tapping into a “divine light” that makes certainty possible. Bonaventure called this divine illumination.

Now, this part gets complicated, but here’s what it accomplishes: it’s a way of saying that knowledge isn’t just a private thing happening inside your skull. Every time you know something for sure, you’re touching something infinite. You might not notice it, but that connection is there.

Path 2: The Argument from the World Around You (More Certain)

This one starts with something you can see and touch. Look at anything—a pencil, a tree, your own hand. Now ask: does this thing have to exist? Could it not exist? Yes, obviously. Pencils wear out. Trees die. Your body will change. Everything you can see is something that exists but could also stop existing.

Bonaventure called this being by participation. Think of a photocopy. The copy has an image, but it got that image from an original. The copy depends on the original. In the same way, everything in the world has “being”—it exists—but it doesn’t have that being from itself. It gets it from somewhere else. Your parents gave you your existence. The food you eat keeps you alive. The sun’s energy powers the plants you eat. Trace it all back, and you eventually need something that doesn’t get its existence from anywhere else—something that just is existence itself.

Bonaventure called this being by essence. If everything that exists “by participation” points to something that exists “by essence,” then you’ve found your way to God. This argument feels more solid than the first one because it starts with real things you can touch, not just ideas in your head.

Path 3: The Argument from the Idea of God Itself (Most Immediate)

This one is the weirdest and the hardest to explain. Bonaventure took it from an earlier philosopher named Anselm, who came up with something called the ontological argument. (Don’t worry about the fancy name—it just means “an argument about being.”)

Here’s the basic idea: think about the phrase “something than which nothing greater can be thought.” You can think that phrase, right? Now ask: does that thing exist? Anselm and Bonaventure said yes, because if it only existed in your mind, you could think of something greater—something that exists both in your mind and in reality. Since you’re already thinking of “the greatest possible thing,” it must exist in reality too.

Bonaventure gave this argument a special twist using the idea of being itself. Think about the word “being” for a second. Everything you’ve ever thought about, you thought of as either a real thing, a possible thing, or a non-thing (like “nothing” or “unicorn”). But notice: to think of a non-thing, you first have to know what “thing” means. And to think of a possible thing, you first have to know what an actual thing is. So “being” is the first idea your mind uses—it’s there before any other idea.

Now, if you take that idea of “being” and strip away everything that limits it—no time, no space, no change, no imperfection—you’re left with pure being. Pure being has no non-being in it at all. And here’s the key: something that has no non-being in it can’t fail to exist. It’s not that it happens to exist—it’s that its very nature is to exist. That’s God.

Bonaventure knew this argument sounds like a trick (a lot of philosophers thought it was a trick). But he insisted it wasn’t. He said the problem is that we’re used to thinking about limited things—pencils, trees, people—that can either exist or not exist. When we try to think about something unlimited, our minds struggle. But the idea is still there, hiding inside every thought you have.

The Bigger Picture: Why All This Matters

So what does Bonaventure want you to take away from all this? Not a tidy proof you can memorize and use to win arguments. Something stranger.

He thought that the universe is like a book written in a language you already know but don’t realize you’re reading. Every physical thing—every tree, every star, every texture and sound—is a sign pointing toward its source. Your own mind, with its ability to know truth and choose goodness, is an even clearer sign. And the very idea of being itself, which you use every time you think anything at all, is the closest sign of all.

You don’t have to be a genius or a saint to follow these clues. Bonaventure was a follower of Francis of Assisi, a man who saw God in birds and wolves and lepers. Francis didn’t need complicated arguments. He just looked at the world and saw a gift. Bonaventure was different—he was a university professor, a master of logic and philosophy. But he used his training to show that Francis’s simple vision was actually supported by the most sophisticated thinking of his time.

The world, Bonaventure said, is a “footprint” of God. Your mind is an “image” of God. And the deepest principles of logic and being themselves point to God. You can follow these signs as far as your curiosity takes you.

Still a Live Debate

Philosophers still argue about all three of Bonaventure’s paths. The ontological argument has fans and critics to this day. The idea of divine illumination sounds strange to most modern thinkers, but some philosophers still defend versions of it. And the argument from participation—that everything imperfect points to something perfect—still shows up in debates about whether the universe needs an explanation.

Nobody has “settled” these questions. Bonaventure would probably say that’s how it should be. Signs aren’t meant to be possessed or conquered. They’re meant to be followed.

Key Terms

Term	What it does in this debate
Vestige	A sign in the physical world that points to God as its cause (like a footprint pointing to an animal)
Image	A sign in the human mind that mirrors something about God’s nature
Divine illumination	The idea that when you know something for certain, your mind is connected to God’s mind
Being by participation	Existence that you get from somewhere else (everything you can see)
Being by essence	Existence that doesn’t come from anywhere else—it just is existence itself
Ontological argument	An argument that tries to prove God exists just by analyzing the idea of “the greatest possible being”
Pure being	The idea of existence with no limits, no non-being, no imperfection

Key People

Bonaventure (1221–1274) – A Franciscan monk and university professor who tried to show that everything—from rocks to your own mind—points toward God. He was elected leader of the Franciscans at 36 and became a cardinal near the end of his life.
Anselm of Canterbury (1033–1109) – A philosopher who first came up with the ontological argument. Bonaventure later improved on Anselm’s version.
Augustine of Hippo (354–430) – An early Christian philosopher whose ideas about the mind and divine illumination heavily influenced Bonaventure.
Francis of Assisi (1181–1226) – The founder of Bonaventure’s religious order, who saw God in nature and in poor people, and whose simple vision Bonaventure tried to defend with philosophical arguments.

Things to Think About

Bonaventure says that when you know something for certain (like 2 + 2 = 4), you’re connected to God’s mind. But what about someone who doesn’t believe in God—are they still connected? And if so, does that mean they believe in God without realizing it?
The ontological argument seems to work like a magic trick: it claims to prove something exists just by thinking about it. Can you find a flaw in the logic? Or does it actually work for you?
If everything in the universe is a “sign” pointing to God, does that change how you’d treat a rock or a tree? Should it? What would it mean to live as if everything you see is a message?
Bonaventure thought that human minds are “images” of God because we have memory, understanding, and will working together. Do you think that’s a good argument, or does it sound like forcing things to fit a pattern?

Where This Shows Up

In science: The question of whether the universe needs an outside explanation (like God) or is self-explanatory is still debated by physicists and philosophers.
In art: Many artists and poets (like William Blake or Gerard Manley Hopkins) have seen the natural world as “charged with the grandeur of God”—full of signs pointing beyond themselves.
In your own experience: Next time you’re absolutely sure about something—a math problem, a moral feeling, a memory you can’t shake—ask yourself where that certainty comes from. Bonaventure would say you’re touching something infinite.
In debates about atheism: The ontological argument keeps being revived and attacked. The philosopher Alvin Plantinga defended a modern version of it in the late 20th century, and people still argue about whether it works.