indefinite article before words beginning with vowels, 12c., from Old English an (with a long vowel) "one; lone," also used as a prefix meaning "single, lone" (as in anboren "only-begotten," anhorn "unicorn," anspræce "speaking as one"). See one for the divergence of that word from this. Also see a, of which this is the older, fuller form.

In other European languages, identity of the indefinite article and the word for "one" remains explicit (French un, German ein, etc.). Old English got by without indefinite articles: He was a good man in Old English was he wæs god man.

In texts of Shakespeare, etc., an as a word introducing a clause stating a condition or comparison conjunction is a reduced form of and in this now-archaic sense of "if" (a usage first attested late 12c.); especially before it.

Old English min "mine, my," (pronoun and adjective), from Proto-Germanic *minaz (source also of Old Frisian, Old Saxon Old High German min, Middle Dutch, Dutch mijn, German mein, Old Norse minn, Gothic meins "my, mine"), from the base of me.

As an adjective, "belonging to me," preceding its noun (which may be omitted), it was superseded from 13c. by my when the noun is expressed. As a noun, "my people, my family," from Old English. In this heart of mine, no fault of mine, etc., the form is a double genitive.

"of thee," Old English þin, possessive pronoun (originally genitive of þu "thou"), from Proto-Germanic *thinaz (source also of Old Frisian, Old Saxon thin, Middle Dutch dijn, Old High German din, German dein, Old Norse þin), from PIE *t(w)eino-, suffixed form of second person singular pronominal base *tu-. See also thou.

the now-little-used 2nd nominative singular personal pronoun, Old English þu, from Proto-Germanic *thu (source also of Old Frisian thu, Middle Dutch and Middle Low German du, Old High German and German du, Old Norse þu, Gothic þu), from PIE *tu-, second person singular pronoun (source also of Latin tu, Irish tu, Welsh ti, Greek su, Lithuanian tu, Old Church Slavonic ty, Sanskrit twa-m).

It was superseded in Middle English by plural form you (from a different root), but retained in certain dialects (e.g. early Quakers). The plural at first was used in addressing superior individuals, later also (to err on the side of propriety) strangers, and ultimately all equals. By c. 1450 the use of thou to address inferiors gave it a tinge of insult unless addressed by parents to children, or intimates to one another. Hence the verb meaning "to use 'thou' to a person" (mid-15c.).

Avaunt, caitiff, dost thou thou me! I am come of good kin, I tell thee!

["Hickscorner," c. 1530]

A brief history of the second person pronoun in English can be found here. Related: Thou-self "you, yourself." Archaic language preserves the enclitic use of it, attached to a preceding auxiliary, artou? hastou?

emphatic form of second-person singular pronoun thy, Middle English þi-self, thi-self, c. 1300; see thy + self. One word from 16c. The Old English was þines silfes. Also used reflexively for emphasis after (or in place of) thou.