Jan Cornelis Sylvius
Johannes Sylvius (1564-1638) was a preacher, first in Sloten (1604) and since 1621 in the Oude Kerk in Amsterdam. He was friend and family of Rembrandt by his marriage to a niece of Saskia, Aeltje Uylenburgh. In 1632 Rembrandt made a painting of Aeltje at the age of 62 (Bredius 333, collection Rose-Marie and Eijk de Mol van Otterloo, Boston). At the ondertrouw, a pre-wedding ceremony, on 10 June 1634 in the Oude Kerk in Amsterdam, it was Sylvius who represented the bride. He also baptized the first two of Rembrandt’s children, Rombartus in 1635 and Cornelia in 1638.