Ink on paper, January 3, 1643, 27.5 x 37 cm. Below the text is the autograph of the duke himself: "Il Prin[cipe] Gio[vanni] Casimoro", and next to it a large, perfectly preserved ducal seal of John Casimir.
The letter is addressed to the Reverend Prelate Onorat Visconti (1585-1645), Bishop of Larissa. In the manuscript, John Casimir sends Bishop Visconti his best wishes and greetings. Onorato Visconti was apostolic nuncio in Poland during the reign of Sigismund III Vasa, father of John Casimir.
The letter is dated 1643 - the year when, against the king's wishes, John Casimir went to Italy and joined the Jesuit order (which he left, however, after two years of novitiate).
