This interesting surname is of medieval Scottish origin, and is a patronymic of the male given name Isaac, itself coming from the Hebrew "Yitschak", a derivative of "tsachak", to laugh. This name was given to the son of Abraham and Sarah, and popular etymology connects the meaning with Sarah's laughter in her joy at bearing a son in her old age. The Greek translators of the Old Testament rendered "Yitschak" as "Isaak"; it was then Latinized into "Isaac". Though popular among Eastern Christians, it occurs only twice in the Old English period as the name of a priest. "Isac" (without surname) occurs in the Domesday Book of 1086, and Isaac was the name borne by the prior of Scone in 1154, while Ysaac of Brechin was a charter witness at St. Andrew's, Scotland, circa 1178. The Gaelic patronymic form of the name appears in the early 13th Century (see below), the prefix "Mac" meaning "son of". In the province of Ulster the name is variously spelt MacKissock and MacKissack. On March 27th 1732, a daughter, Mary, was born to Neil McIsaac and Mary McClean, in Edinburgh, Midlothian. The first recorded spelling of the family name is shown to be that of Gillandes Macysac, which was dated 1231, a charter witness, in the "Charters of the Priory of Beauly", Inverness-shire, Scotland, during the reign of King Alexander 11 of Scotland, 1214 - 1249. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.