All of the characters in "The Knight's Tale" believe that larger forces are at work behind everything that happens to them, deciding their destinies in love and life, and determining the time and circumstances of their deaths. Variously called "Fortune," "destynee," any one of the gods, or the "Firste Moevere," this mysterious force writes people's fates in the stars. As Theseus reminds everyone in his "First Moevere" speech, it is pointless to rage against fate. Still, he's confident that the First Mover has a plan, and that what may seem senseless is actually part of something larger than ourselves.
All this talk about destiny and fate raises the question of how much responsibility an individual has for the course of his life. But the thing is, "The Knight's Tale" isn't really concerned with that question. Instead, it points to the fruitlessness of trying to shape one's own destiny. The proper way to live your life is simply to accept your fate with patience and to try to make the best of it.
"The Knight's Tale" portrays the events in a character's life as a result of forces beyond his control.
"The Knight's Tale" suggests that the only control you have over your life is your attitude toward whatever fate throws your way.