Okay, that's it. Education time. Old Singular - Old Plural - Modern Thou - Ye - You Thee - You - You Thy - Your - Your Thine - Your - Your Thou and thee are used like I and me respectively while thy and thine are mostly interchangable. However, thine is usually used before words beginning with a vowel and thy before those beginning with a consonant. Otherwise, thy and thine behave like my and mine respectively. Additionally, many verbs have a "Thou form." Shall's thou form is shalt. The thou form usually consists of "est" tacked onto the end. Now, stop saying "Thy shalt." In fact, stop using thy where it's clearly not appropriate. That is, where possession is not involved.