“Anxiety is love’s greatest killer,” Anaïs Nin admonished.“It makes others feel as you might when a drowning man holds on to you. You want to save him, but you know he will strangle you with his panic.” No form of anxiety sinks the buoyancy of love more readily than jealousy. The Swiss philosopher Henri-Frédéric Amiel put it best in his reflections on love and its demons: “Jealousy… is precisely love’s contrary… the most passionate form of egotism, the glorification of a despotic, exacting, and vain ego, which can neither forget nor subordinate itself.”

Indeed, this corrosive yet common human experience is one which responds better to being befriended rather than forcefully subordinated, for the more one denies and resists it, the more it persists. How to accept it as natural and, in that acceptance, let it dissolve is what the trailblazing French mathematician Émilie du Châtelet (December 17, 1706–September 10, 1749) explores in a letter to one of her lovers, found in her Selected Philosophical and Scientific Writings (public library).

What made Du Châtelet particularly extraordinary is that her rigorous scientific mind came coupled with immensely sensitive insight into the workings of the human heart. In the late spring of 1735, the 29-year-old mathematician — who had enchanted Voltaire two years earlier and would soon popularize Newton and lead the way for women in science — writes to Louis François Armand de Vignerot du Plessis, Duke of Richelieu, a notorious playboy:

There is much difference between jealousy and the fear of not being loved enough: one can brave the one when one feels that one does not merit it, but one cannot help being touched and distressed by the other. Jealousy is an annoying feeling, and the fear of it a delicate anxiety, against which there are fewer weapons and fewer remedies, other than to go to be happy… There, in truth, is the metaphysics of love, and this is where the excess of this passion leads. All this appears to me as the clearest and most natural thing in the world.

In the same letter, Du Châtelet models the counterpoint to jealousy’s contracted clutch — the largeness of heart and generosity of spirit that loves another unconditionally in their imperfect entirety, excludes nothing from the scope of that love, and longs to partake in the other’s completeness. Using the French word amitie, which connotes affectionate friendship and which Du Châtelet imbues with distinct romantic hues in her correspondence, she addresses her lover:

It is the privilege of affection to see a friend in all the situations of his soul. I love you sad, gay, lively, blocked; I want my friendly feelings to add to your pleasures and diminish your troubles, and I want to share them.

Complement Du Châtelet’s altogether electrifying Selected Philosophical and Scientific Writings with her prescient 18th-century reflection on gender in science and the nature of genius, then revisit philosopher Martha Nussbaum on jealousy as illuminated by anger and forgiveness.