Many modern uses of English J go back to Latin consonantal I. The Roman gods whom we call Jupiter, Juno, and Janus actually had Latin names Iuppiter, Iuno, and Ianus (pronounced “Yupp-piter,” “Yoono,” “Yahnus”). Janus was patron god of the doorway ( ianua ), connected also to the Roman word for door-keeper, ianitor, whence our janitor. The Roman calendar opened with the month of Ianuarius, January. Julius Caesar was actually named Iulius (Yoolius).