Thee and thou, over and out
Though thee and thou sound formal to modern ears—as in "Ah, silly Pug, wert thou so sore afraid?"—they were originally used as intimate versions of the second person pronoun. Mark Kleiman at the The Atlantic examines the origins and evolution of thee and thou - and identifies what pronoun the ever-evolving English language might lack today.
Take thee to Atlantic’s culture blog:
Of course, the pressing need in English today is not for a second-person singular but for a neuter third-person singular, to avoid the clumsy "his or her" formulations. On this point, the demos has spoken, adopting the plural they/them/their in place of the neuter singular. Someone just suggested replacing the motto of the Reality Based Community, "Everyone is entitled to his own opinion, but not his own facts," with "their own opinion," etc. I refused, partly because the motto is a quotation from Pat Moynihan, who is no longer around to consent to the change, but more because I'm an old prescriptivist fuddy-duddy and the use of plural for singular sounds illiterate to my aging ear . . .