ABSTRACT
Gottfried Wilhelm Leibniz, the seventeenth-century German philosopher and mathematician, formulated the principle of the identity of the indiscernibles, which states that if it is not possible to establish a difference between two objects, they are identical. Since it is not possible to distinguish between two identical objects, an interchange in their positions has no effect in the physical state of the two objects or of the system they belong to. This interchange is an example of what a mathematician calls symmetry.
