But to this calculus, all-powerful so long as it does not leave the domain of the ideal, let us submit a very modest reality: the fall of a grain of sand, the Pendular movement of a hanging body.
"More Hunting Wasps"
J. Henri Fabre
It must have an ideal material point, an ideal rigid thread, an ideal point of suspension; and then the Pendular movement is translated by a formula.
"More Hunting Wasps"
J. Henri Fabre