The paper focuses on ontology and epistemology of the founder of Da-sein analysis Ludwig Binswanger. There are two conceptions which contributed immensely to the Binswanger's analysis: Heidegger's understanding of human being as disclosedness of being; and the philosophy of dialogue, as far as it is orientated to consider the true being, not as a self-closed and self-isolated the Self (Ego), but the transcendentally-immanent being of “We”, to which Simon Frank's ontology also belongs. It is analyzed how Binswanger transforms Heideggerian set on Da-sein as “always mine” to acknowledge the dual being of We or love as the basic anthropological phenomenon. Concerning Frank, the comparative analysis finds its foundation in Binswanger's own multiple admissions of his solidarity with Frank that have been uttered by him in his memories, correspondence, and the book “Basic Forms and the Knowledge of Human Presence”. It is examined the common positions of Binswanger's and Frank's ontology that come from the common set on “ontologism”, which conditions the possibility of notional (conceptual) knowledge with the immediate knowledge of absolute being, founded on belonging of the subject to this being. It is analyzed specifics of Binswangerian ontologism, expressed in his understanding of the being of We or love as a coincidence of being and knowledge. The paper analyses the motives of love as absolute being, mystical images and concepts, used by Binswanger. All these images and concepts he borrows directly from Neo-Platonism, German mystics, and Frank's works. The paper also traces a number of parallels between Binswanger's and Frank's theories of knowledge. By this, we mean two orders of knowledge: the notional knowledge and the knowledge of Da-sein as the metalogical foundation of the former. The paper's conclusions deal with the analyis of antinomies in Binswanger's conception. The conception, on the one hand, tends to narrow of differences between the being We with Absolute being, knowledge of Da-sein as love with mystical knowledge of the Absolute, as on the other hand, it is an effort to think about being of We as a merely human being.