This early medieval English surname recorded in the spellings of Sealey, Seally, Sealy, Seelly, Siley, Silley, Zealey, and other rare forms is of pre 7th century origins. It derives from the use of the word "saelig", meaning happiness and good fortune and given either as a baptismal name, or as a nickname of endearment for someone with a cheerful disposition. In the Middle Ages around the 13th century, the spelling form changed to "seely", and from this spelling developed the later surnames. The word was also used as a female personal name, being recorded as "Sely" (the modern Celia) in 1221, and this was also a source for some bearers of the modern surname. Early examples of the surname recordings include Richard Sely and John Celi who both appear in the 1275 Hundred Rolls of Worcester, whilst Thomas Zely is recorded in the same place but in 1327. Church register recordings include Isaak Seeley, christened at Holy Trinity in the Minories, London, on October 3rd 1565, Jone Syley at St Botolphs Bishopgate, on April 17th 1567, Ellen Silly at St Dunstans Stepney on June 19th 1634, and Mary Siley at St Mary Le Strand, Westminster, on May 18th 1854. William Sealy, who in 1635 left London on the ship "Alexander", bound for the New World, was one of the first American settlers. The first recorded spelling of the family name is shown to be that of Richard Seli, which was dated 1201, recorded in the "Gilbertine Charters of London", during the reign of King John, known as "Lackland", 1199 - 1216. 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.