‘Gravity Explains the Motions of the Planets’ – Newton’s Quote

Quote Analysis

Isaac Newton, one of the greatest scientific minds in history, revolutionized our understanding of the universe with his laws of motion and gravitation. Yet, despite his groundbreaking discoveries, he remained acutely aware of science’s limitations. His statement:

“Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion,”

reveals a deeper philosophical concern—one that bridges science, metaphysics, and theology. Why did Newton, a man of reason, invoke a higher cause beyond natural law? In this article, we’ll explore the profound meaning behind this quote and why it continues to challenge modern thinkers.

Origin of the Quote and the Context of Newton’s Thought

Isaac Newton is often remembered as the father of classical physics—the man who gave us the laws of motion and universal gravitation. But what many people overlook is that Newton was also deeply philosophical and religious. The quote “Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion” captures this lesser-known side of his thinking.

This quote was not pulled from a casual conversation—it reflects Newton’s lifelong engagement with both natural philosophy and theology. Although he developed a mathematical framework that could describe the orbits of planets with great precision, Newton believed that behind these elegant laws stood a divine Creator. For him, scientific laws described what happens and how it happens, but they could never fully explain why it happens—or who made it happen in the first place.

This belief was consistent with Newton’s time. In the 17th century, science and theology were not considered enemies. Many scientists, including Newton, saw no contradiction between studying the natural world and believing in a purposeful universe created by God. In fact, Newton saw his scientific work as a way of understanding God’s design.

So, when Newton made this statement, he wasn’t dismissing science—he was pointing out its boundaries. He was acknowledging that scientific explanation has limits, and that some answers might lie outside the reach of equations and observations.

Meaning of the Quote: The Limits of Scientific Explanation

To understand the heart of Newton’s quote, we need to make a clear distinction between describing a process and explaining its origin.

When Newton says, “Gravity explains the motions of the planets,” he refers to the way gravity governs how planets move—how they orbit the sun, how they affect one another, and how their paths can be predicted. This is the realm of science: describing patterns, building models, and calculating outcomes. It’s about the mechanics of the universe.

But when he adds, “but it cannot explain who sets the planets in motion,” Newton shifts from science to a philosophical and theological question. He’s asking: What caused the whole system to begin? Who—or what—initiated motion in the first place?

Science, by its nature, deals with what can be measured, observed, and tested. It can tell us how gravity works, but it doesn’t answer why there is a gravitational force at all, or why the universe exists with order and intelligibility. That kind of question falls into the domain of metaphysics and theology.

Here’s a simple comparison to help clarify the idea:

Science can describe how a clock works—its gears, springs, and hands.
But science doesn’t tell us who made the clock or why it was made.

In this quote, Newton reminds us that scientific knowledge is powerful, but not all-encompassing. There are questions—big, meaningful questions—that science leaves unanswered. This doesn’t weaken science; it simply shows that it’s one tool among many for understanding reality. Newton invites us to consider that behind natural law may stand something—or someone—greater than the laws themselves.

A Scientist Who Believed: Newton’s Spiritual Dimension

Although Isaac Newton is most famous for his groundbreaking scientific work, especially in physics and mathematics, it’s important to understand that he also spent a large part of his life studying theology. In fact, he likely wrote more about religion and biblical interpretation than about physics. This surprises many people today, but for Newton, science and faith were deeply connected.

Newton did not see the universe as a cold, mechanical system running on its own. He saw it as a carefully designed creation that reflected the intelligence and purpose of its Creator—God. So when he said that gravity explains how the planets move but not who put them in motion, he wasn’t being poetic. He was making a serious theological statement.

He believed that:

Natural laws, like gravity, are tools used by God to govern the universe.
The harmony and order in nature are not accidents but signs of divine design.
Scientific discovery is a way to glorify God by uncovering the structure He created.

Newton rejected the idea that the universe could operate entirely on its own without divine guidance. He believed that a world without God would eventually fall into disorder. For him, God was not just a distant creator who set the universe spinning and walked away; God was actively present in maintaining the system, moment by moment.

This view is part of what is known as natural theology—a belief that we can come to understand certain things about God by studying nature. Newton saw no contradiction in being a brilliant scientist and a devout believer. Instead, his faith gave meaning and purpose to his science.

Philosophical Implications: Theory vs. Ultimate Cause

Let’s now turn to the deeper philosophical meaning behind Newton’s quote. It’s not just a comment on science; it’s a reflection on the difference between explaining how something works and explaining why it exists at all.

In philosophy, there is a distinction between proximate causes and ultimate causes.

A proximate cause is something immediate and observable. For example, gravity is the proximate cause of why the Earth orbits the Sun.
An ultimate cause is a deeper explanation—it asks: Why is there gravity at all? Why is there a universe that follows laws instead of chaos?

Newton’s quote touches on this distinction. Science deals mostly with proximate causes. It builds models, runs experiments, and draws conclusions about how things behave. But the moment you ask why those laws exist or what gave rise to the entire system, you’ve stepped into philosophy—and possibly theology.

This is very similar to what earlier thinkers like Aristotle and Thomas Aquinas discussed. They argued that there must be a “first mover” or “unmoved mover”—something that caused all motion and change but was not itself caused by anything else. Newton’s quote fits into that tradition. He’s not abandoning science; he’s recognizing its limits and pointing beyond them.

Here’s a classroom analogy:
Imagine you’re watching a video of a domino chain falling. Science can tell you how each domino hits the next and calculate the speed, angle, and force. But someone still had to line up the dominoes and give the first push. Newton is asking: Who gave the first push to the universe?

That’s not something physics can answer—and Newton didn’t think it should. For that, we need to turn to broader human reasoning: philosophy, theology, and metaphysics.

Modern Reflections: What Does This Quote Mean Today?

Although Newton lived in the 17th century, the question he raised in this quote still matters today. In fact, it’s more relevant than ever. Modern science has made incredible progress—quantum mechanics, general relativity, cosmology, and particle physics have expanded our understanding of the universe far beyond anything Newton imagined. But the deeper questions remain.

Today, many scientists work from the assumption that the universe operates without purpose or intention—just physical laws acting on matter. In this view, there’s no need for a “who” behind the motion of the planets. The system just is. But even now, some scientists and philosophers challenge this assumption.

Let’s look at some modern perspectives:

Stephen Hawking once suggested that because of laws like gravity, the universe can and will create itself from nothing. Yet, this still assumes that the laws of physics already exist. But where did those laws come from?
Albert Einstein didn’t believe in a personal God, but he often spoke about a sense of awe before the structure and harmony of the cosmos. He famously said, “The most incomprehensible thing about the universe is that it is comprehensible.”
Philosophers of science like Thomas Nagel and Alvin Plantinga have argued that a purely materialistic view of the universe leaves many questions unanswered—especially about consciousness, morality, and the origin of physical laws.

In short, Newton’s quote invites us to stay humble. No matter how advanced our models become, they still operate within a framework that we didn’t create. Newton’s insight reminds us that it’s reasonable—even necessary—to ask what lies behind the curtain of scientific explanation.

Related Quotes and Thoughts from Great Minds

Newton’s quote is part of a larger tradition of thinkers who recognized the limits of human reason and the possible need for something beyond science to fully explain reality. Many famous figures have echoed similar thoughts.

Here are a few notable examples:

Albert Einstein: “Science without religion is lame, religion without science is blind.”
Einstein believed that science and spirituality should not be enemies, but allies. He often spoke about the mystery and order of the universe as something that inspired reverence.
Blaise Pascal: “The heart has its reasons which reason does not know.”
Pascal argued that human understanding is not purely rational—that some truths are known through the heart, not through logic alone.
Stephen Jay Gould: He proposed the idea of “Non-Overlapping Magisteria” (NOMA), which suggests that science and religion answer different types of questions: science tells us how the world works, while religion explores meaning and moral value.
Werner Heisenberg: “The first gulp from the glass of natural sciences will turn you into an atheist, but at the bottom of the glass God is waiting for you.”
This quote reflects the idea that deep exploration of nature can bring one back to fundamental existential and spiritual questions.

What all these thinkers have in common is the belief that science is powerful, but not self-sufficient. Newton’s quote belongs among these voices, reminding us that human curiosity should not stop at the measurable.

Science, Faith, and the Eternal Question of Cause

Newton’s quote does more than express a personal belief—it poses a timeless philosophical challenge. Can science alone explain the origin of everything? Or is there something—someone—behind the curtain?

Let’s remember that Newton was not trying to weaken science. He strengthened it more than almost any other individual in history. But he also recognized its boundaries. He understood that scientific laws describe patterns, not purposes; that they measure motion, but don’t explain motivation.

So what can we take away from this?

Scientific knowledge is incredibly valuable, but it may never answer questions like “Why is there something rather than nothing?”
It’s intellectually honest to admit when our tools—however precise—aren’t suited for certain kinds of questions.
Philosophy and theology are not enemies of science; they can help explore the bigger picture.

Newton invites us not just to look at the stars, but to wonder why there are stars at all—and who lit them in the first place. That question, perhaps, is the beginning of wisdom.

‘Gravity Explains the Motions of the Planets’ – Newton’s Quote and the Limits of Scientific Explanation