The Origin of Descartes Heart Line
Descartes sent Christine his thirteenth letter and died forever. At this time, the little princess under house arrest is still wandering in the corridor of the palace, thinking of her lover in the distance. There is not a word written in this last letter, but only one equation: r=a( 1-sinθ). He couldn't bear to see his beloved daughter moping every day, so he gave her this letter.
Christine was ecstatic when she received the letter. She immediately understood her lover's intention and began to draw equation diagrams. A heart-shaped pattern appeared in front of her eyes. This curve is the famous heart line. After Christine ascended the throne, she immediately sent someone to France to find the whereabouts of her sweetheart, but she received the news of Descartes' death, leaving eternal regret. This world-famous alternative love letter is still preserved in the Descartes Memorial Hall in Europe to commemorate this beautiful love.