"Cum non solum" (Since not only men but also irrational animals and even the very elements of the world machine have been connected by a certain unity of natural affinity on the model of the heavenly spirits,.....)was a letter written by Pope Innocent IV to the Mongols on March 13, 1245.

It was common to label a document by it's first three words at the time.

In it, Pope Innocent appealed to the Mongols to desist from attacking Christians and other nations, and inquires as to the Mongols' future intentions. Innocent also expresses a desire for peace (possibly unaware that in the Mongol vocabulary, "peace" is a synonym for "subjection").

This message was carried by the Franciscan John of Plano Carpini and delivered to the new Khan, and Guyuk Khan did indeed misunderstand the Pope's plea

He replied to the Pope's letter with a fairly typical Mongol demand for the Pope's submission, and a visit from the rulers of the West in homage to Mongol power.

More Info: en.wikipedia.org