One of Shakespeare's favorite themes is that of destiny and fate. Does man control his own destiny, or is he a victim of fate?

One of Shakespeare's favorite themes is that of destiny and fate. Does man control his own destiny, or is he a victim of fate? Do you think that Cassius' bad feelings made him interpret his army's victory as defeat and then cause his suicide? Talk about the theme of fate in Julius Caesar. Does man control his own destiny or not?