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“What is toleration? It is the appurtenance of humanity. We are all full of weakness and errors; let us mutually pardon each other our follies—it is the first law of nature.”
Voltaire begins toleration from shared human fallibility: recognizing that everyone is capable of error weakens the claim that disagreement should be answered with persecution.
Source note: A Philosophical Dictionary, article “Toleration,” Project Gutenberg #35630. The section moves immediately into examples of people from different religious traditions trading together without attacking one another, placing the maxim inside Voltaire’s campaign against religious persecution.