The 557 letters that Goethe wrote in 1780 and 1781 testify to his various interests and his increasing official activities. Along with Knebel, Lavater, Fritzsch, and Herzog Carl August, the 51 people to whom he wrote during this time include Ernest II, Duke of Saxe-Gotha-Altenburg, and Prince August. Nearly three-quarters of the letters are addressed to Charlotte von Stein, his most important correspondent.