A human being is composed of a body and a mind. A body without a mind is just a dead corpse. A mind without a body is just pure spirit. Someone who, although endowed with both body and a mind, only knows the body but not the mind is called a sentient being. In general, a sentient being is understood as any being possessing conscious life. Birds flying in the sky, animals walking on the ground, fish swimming in the water, as well as the tiniest organisms, are all sentient beings.
Human beings are said to be superior to all other creatures. But how can a human being be considered superior if he knows his body but is ignorant of the nature of his mind? One who knows the body but not the mind is an incomplete person. However, if a human being searches for the mind and awakens to it, he will realize completeness; for at that time he will know both the body and the mind.
The purpose of practicing Zen meditation is to awaken to the mind. What is the mind? What you are searching for can be called by many different names; mind, spirit, soul, true nature, and so forth. But such designations are merely labels. You should put aside all of these names and reflect on the fact that the true master of the body is more than just a label "mind." The master of the body is not the Buddha, for it is not yet awakened. Nor is it anything material, because it cannot be physically given away or received. Nor is it simply empty space, for empty space cannot pose questions or have knowledge of good and evil.
Hence there is a master who rules this body who is neither the label "mind," the Buddha, a material thing nor empty space. Having negated these four possibilities, a question will arise as to what this master really is. If you continue inquiring in this way, the question will become more intense. Finally, when the mass of questioning enlarges to a critical point, it will suddenly burst. The entire universe will be shattered and only your original nature will appear before you. In this way you will awaken.
Master Su San Sunim
The Way of Korean Zen