He was born Jewish, became a priest, fathered seven children and was tried and found guilty of vice. He was a poet, playwright, linguist, professor, opera impresario and grocer. He lived in Venice, London and Vienna, but spent the last 30 years of his life in New York, where he became an American citizen. He knew Casanova, Mozart and Salieri and dined with James Fenimore Cooper, Henry Wadsworth Longfellow and Washington Irving. His portrait was painted by the code-developer Samuel Morse. Thousands attended his funeral, but no one knows where his grave is. He is Mozart’s librettist, Lorenzo da Ponte, …