What does thyself mean in shakespearean times?

In Shakespearean times, "thyself" was used as a reflexive pronoun, similar to how we use "yourself" today. It was used to refer to the person speaking or being spoken to, and was often used in place of "you" or "your." For example, instead of saying "You should do this," someone might say "Thou shouldst do this." Similarly, instead of saying "Your opinion is important," someone might say "Thine opinion is important." Additionally, "thyself" could be used to emphasize the person being spoken to, as in the phrase "Thou thyself art the key."