Daniel ben Abraham de Fonseca (ca. 1668–ca. 1740) was a Jewish physician of Iberian origin who achieved prominence for his involvement in Ottoman diplomacy. Born into a marrano family in the Portuguese city of Porto, Fonseca grew up as a Christian after his grandfather and uncle were burned at the stake and his father fled the country. Although he was baptized and joined the priesthood, he practiced the Jewish faith secretly and eventually went to France, where he studied medicine in Bordeaux and Paris. Sometime between 1680 and 1702, he arrived Istanbul, where he reverted to Judais…