What does the phrase pull your strings mean?
Pulling your strings means to treat your like you are someones puppet or a marionette like Pinocchio (the puppet on a string).
http://www.shopfloortalk.com/forums/showthread.php?p=80749 The average medium sized piano has about 230 strings, each string having about 165 pounds of tension, with the combined pull of all strings equaling approximately eighteen tons. A person high strung would very tense, as in a piano. That's where the phrase "high strung" came from.