One of the aims of the "Essay" was to provide a replacement for the Latin language, which had been the international language of scholars in Western Europe by then for 1000 years. Comenius and others interested in international languages had criticisms of the arbitrary features of Latin that made it harder to learn, and Wilkins also made such points. A scheme for a "lingua franca" based on numerical values had been published by John Pell (1630); and in his 1640 work "Mercury or the Secret Messenger" (1640) Wilkins had mentioned the possibility of developing a trade language.