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The Philosopher’s Plant 7.0: Leibniz’s Blades of Grass

The year: 1685. The place: the gardens of Herrenhausen, the Electoral Palace of Princess Sophie in Hanover.

A frantic search is under way, led by the distinguished courtier Carl August von Alvensleben. No, the ladies and gentlemen of the Hanover court were not looking for a lost earing of Princess Sophie. The object of their quest was much more prosaic than that; they tried to find two leaves that would be exactly alike. Why this sudden obsession with the plants growing in an undeniably magnificent Baroque garden, the most emblematic of its kind in Europe?

The answer thrusts us into the thicket of Gottfried Wilhelm Leibniz’s philosophy and introduces one of its pivotal principles, which von Alvensleben attempted to refute in the crudest empirical way imaginable.

Fast forward to June 2, 1716. In a letter addressed to English philosopher Samuel Clarke, Leibniz recalls the garden episode in connection to his famous principle of the identity of indiscernibles, or, simply put, “Leibniz Law”: