Thou, Thee, Thy, and Thine

The words "thou", "thee", "thy", and "thine" are archaic English
seconf person singlar pronouns. 

"Thou" is the subjective form. "Thee" is the objective form. "Thy"
and "thine" are the possessive forms, with "thine" used before words
beginning with "h" or a vowel, and "thy" before other consonants.

With these pronouns, present tense verbs generally took the -est
ending. "To be" ("art") and "to have" ("hast") were irregular.

From around 1450, "you", which had previously been used only as a
second person plural pronoun, began to be used as a second person
singular pronoun to indicate politeness. "You" eventually replaced
all the "thou" pronouns in most English dialects.

Refeence: A. Davies, R. Lipton, D. Richoux, et al. "Thou, Thee, and
Archaic
Grammar". alt.usage.english. <http://www.alt-usage-english.org/pronoun_paradigms.html>.