Seeing as our human cognition differs greatly from cognition of every other material being it is the goal of this paper to unveil all specific features concerning the human mind. Starting from common sense knowledge we possess and our own experience of the outside world, as well as the world inside us, we come to understand our own cognition which shows itself to be non-material. The first step we took was the explanation of sensory cognition which is actually a precondition to all our further knowledge because without the reliance on matter or material beings, which surround us, we are not capable of comprehending anything else. Moreover, that material beings exist will be shown to be the first common sense knowledge our mind comes to understand. Building on such firm grounds, grounds of common sense knowledge of the experience we have of the world, we ascend to mental cognition and the cognition of our own self where we also come to understand why is our knowledge of the world certain and why, by knowing sensory, and by that also material, elements of reality, we have the ability to comprehend non-material beings. The last step in the study of metaphysics of the human mind is the exploration of its cause which shows itself to be the human soul. Although the human soul, in a sense, could be considered as common sense knowledge, the problem of the soul occupied a great deal of thought and human endeavour in the history of mankind. Along with the brief exposition of thought about the soul from ancient philosophers, the paper also shows how and why is the soul source of all human life and not just his mental cognition. Besides that, we state the reasons why the soul provides us with immortality by means of three arguments we find in thomistic philosophy.