I can measure the motion of bodies but I cannot measure human folly.
Interpretation
Newton acknowledges the limits of scientific measurement in understanding human behavior.
In this quote, Isaac Newton reflects on the distinction between the measurable elements of the physical world and the complexities of human behavior. While he is confident in his ability to quantify the laws of motion, he acknowledges a fundamental limitation in trying to quantify the irrational and unpredictable aspects of human nature, suggesting that folly cannot be accurately measured or categorized like physical laws.
In practice
During a lecture on the limitations of science, one might quote Newton to illustrate the unpredictability of human decisions.
The best and safest way of philosophising seems to be, first to enquire diligently into the properties of things, and to establish those properties by experiences [experiments] and then to proceed slowly to hypotheses for the explanation of them. For hypotheses should be employed only in explaining the properties of things, but not assumed in determining them; unless so far as they may furnish experiments.
Plato is my friend, Aristotle is my friend, but my greatest friend is truth.
His epitaph: Who, by vigor of mind almost divine, the motions and figures of the planets, the paths of comets, and the tides of the seas first demonstrated.
And from true lordship it follows that the true God is living, intelligent, and powerful; from the other perfections, that he is supreme, or supremely perfect. He is eternal and infinite, omnipotent and omniscient; that is, he endures from eternity to eternity; and he is present from infinity to infinity; he rules all things, and he knows all things that happen or can happen.
My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments: In order to which, I shall premise the following Definitions and Axioms.
It is the weight, not numbers of experiments that is to be regarded.
The only thing grief has taught me is to know how shallow it is.
We come into the world alone and we die alone. Why, in life, should we be any less alone?
Fantasy is silver and scarlet, indigo and azure, obsidian veined with gold and lapis lazuli. Reality is plywood and plastic, done up in mud brown and olive drab. Fantasy tastes of habaneros and honey, cinnamon and cloves, rare red meat and wines as sweet as summer. Reality is beans and tofu, and ashes at the end.
The true end of tragedy is to purify the passions.
Make women rational creatures, and free citizens, and they will quickly become good wives; - that is, if men do not neglect the duties of husbands and fathers.
The custom and fashion of today will be the awkwardness and outrage of tomorrow - so arbitrary are these transient laws.
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