ABSTRACT. Husserl claims the possibility of a universal neutrality modification affecting every positing act. Bolzano uses "existence" and "being" synonymously with "actuality", and accordingly says of non-actual objects that they do not exist, but that they merely are. Heidegger writes that Dasein can, in principle, become its authentic self. Dasein can become total because it is an entity which can take its past, present and future Being into a unified whole.