I think Macbeth is trying to say that life is meaningless as he says “To-morrow, and to-morrow, and to-morrow,Creeps in this petty pace from day to day” what he is saying about life is that life is dangerous as time will try to creep up on you and try to attack when you are not ready as he says creeps in this petty pace saying time moves slowly but will catch up and get you with a surprise attack as you wont see it coming. When he says about all our yesterdays have enlightened fools. What he is trying to say about life is that people that are interested in others history are fools to be interested in people’s past/history. The way to dusty death is saying that as you live you are going to a journey to a dusty death and that no one will care when you die as this journey is pointless as a dry and boring life.