This surname was derived from the Hebrew male given name YITSCHAK, a derivative of TSCAHAK, meaning to laugh. This was the name of the son of Abraham (Genesis.21.3) the traditional explanation of the name is that Abraham and Sarah laughed with joy at the birth of a son to them in their old age, but a more plausible explanation is that the name originally meant 'May God laugh'. i.e. to smile on him. Like Abraham this name has always been immensely popular among Jews and was also widely used in medieval Europe among Christians. Hence it is the name of many gentile families. In Eastern Europe the given name was popular in both Orthodox Russian and Bulgarian, Polish and Czechosovakia Churches. The name was borne by a 5th century father of the Armenian Church, and by a Spanish saint martyred by the Moorish rulers of Cordoba in AD 842 on account of his polemics against Islam. Notables of the name include ISAAC I (died 1061) the eastern Roman emperor in Constantinople from 1057 to 1059. He established the finances of the empire on a sounder footing, laid the clergy under contribution at the tax collections, and repelled the Hungarians attacking his northern frontier; and then resigning the crown (1059) retired to a monastery, where he died. Angellus ISAAC II (died 1204) was the eastern Roman emperor in Constantinople from 1185. After a reign of war and tumult he was dethroned, blinded and imprisoned by his brother Alexius in 1195. Restored in 1203, he reigned for six months, was again dethroned and died in prison. When traditional Jews were forced to take family names by the local bureaucracy, it was an obligation imposed from outside traditional society, and people often took the names playfully and let their imaginations run wild by choosing names which either corresponded to nothing real in their world. No one alive today can remember the times when Jews took or were given family names (for most Ashkenazim this was the end of the 18th century or the beginning of the 19th) although many remember names being changed after emigration to other countries, such as the United States and Israel in recent years.