Problem: "Existentialists like to say that man is in anguish. This is what they mean: a man who commits himself, and who realizes that he is not only the individual that he chooses to be, but also a legislator choosing at the same time what humanity as a whole should be, cannot help but be aware of his own full and profound responsibility" (pg. 25). "The anguish we are concerned with is not the kind that could lead to quietism or inaction. It is the anguish pure and simple, of the kind experienced by all who have borne responsibilities" (pg. 27). "And when we speak of 'abandonment' - one of Heidegger's favorite expressions - we merely mean to say that God does not exist, and that we must bear the full consequences of that assertion" (pg. 27). could you explain these quotes?