"While Catherine also flattered Voltaire in her letters, she wrote in a more contrived manner, perhaps due to the fact that her secretary Pictet thoroughly revised the letters (unlike the letters she wrote to Frederick the Great) prior to sending them.The main difference between the two sets of letters seems to be that "[Catherine] compliments Voltaire, to tickle his vanity and play on his prejudices", while Voltaire's compliments "convey undertones of hero-worship."