One of the epistemological problems presented by Kant was a question whether or not our intellect can attain to the objective reality, i.e. thing-in-itself. In the pursuit of this problem he considered "quid juris" very important. The objective validity of our concepts of which we make use in our cognition, he thought, could be demonstrated by the deduction in "quid juris", because he believed that the concepts are all apriori. But really are these concepts all apriori ? In order to give an answer to this question, I take up the ontological relations of "recipiens" to "receptum"-these are often used in the scholastic theory of cognition, especially in Aquinas' dictum-and inquire into how Kant had to take a theory of consciousness in his epistemology. In this paper, therefore, I first of all am concerned with the phenomenal fact of consciousness, which is thought as the immediate given of "something" in recipiens. In it are involved an experimental cognition, i.e. a direct reception of there being a something, and a cognition of essence, i.e. a direct apprehension of to be of that thing. What is thought, in a consciousness, as if it were the nature of the being of consciousness as receptum, is only a form of thinking as an act of consciousness as recipiens. And yet, Kant considered it as the nature of consciousness as receptum, so he thought that there would be the awareness of comprehension of the concept of essence of "something", because there was the immediate given of "something". So I secondly illustrate two sorts of knowing by which we apprehend things, that is, cognitio experimentalis quantum ad ordinem existentiae and cognitio conceptualis quantum ad ordinem essentiae, and attempt to correct the errors in Kant's analysis of the phenomenon of consciousness.