Originally Posted by [url=http://en.wikipedia.org/wiki/You]You - Wikipedia[/url]
Early Modern English distinguished between the plural you and the singular thou. This distinction was lost in modern English due to the importation from France of a Romance linguistic feature which is commonly called the T-V distinction. This distinction made the plural forms more respectful and deferential; they were used to address strangers and social superiors. This distinction ultimately led to familiar thou becoming obsolete in standard English (and Dutch), although this did not happen in other languages such as French. Ironically, the fact that thou is now seen primarily in literary sources such as King James Bible (often as words from God) or Shakespeare (often in dramatic dialogs, e.g. "Wherefore art thou Romeo?") has led many modern anglophones to erroneously perceive it as more formal, not familiar (case in point: in Star Wars: The Empire Strikes Back, Darth Vader addresses the Emperor saying, "What is thy bidding, my master?").