The following explanation of the Buddhist practice of mindfulness has been abridged from the beginning of the text Satipatthana Vipassana by The Venerable Mahasi Sayadaw Agga Maha Pandita.

The method of developing wisdom is to observe matter and mind, which are the two sole elements existing in a body, with a view to know them in their true form. Experiments in the analytical observation of matter are usually carried out in laboratories with the aid of various kinds of instruments. Yet these methods cannot deal with mind stuff. The Buddhist method does not, however, require any kind of instruments or outside aid. It can successfully deal with both matter and mind. It makes use of one’s own mind for analytical purpose by fixing bare attention on the activities of matter and mind as they occur in the body. By continually repeating this form of exercise, the necessary concentration can be gained and when the concentration is keen enough, the ceaseless course of arising and passing away of matter and mind will be vividly perceptible.

The body consists solely of two distinct groups of matter and mind. The solid substance of the body constitutes a mass of matter. Matter changes its form under physical conditions of heat and cold. Under such contrary physical conditions, it is called Rupa (form). In the Abhidharma, the proper name for the third division of the Buddhist scriptures dealing with the metaphysical and psychological, the elements of mind and matter are classified differently as ‘Things Which Possess Consciousness’ and ‘Things Which Lack Consciousness’ (Sarammana Dharma and Anarammana Dharma) respectively. The element of mind has an object, or holds an object, or knows an object while that of matter does not have an object, nor holds an object, nor knows an object. There is no faculty of knowing an object in the element of matter.

A Yogi (mediator) also perceives in like manner, that is, “Material element has no faculty of knowing”. Logs and pillars, bricks and stones and lumps of earth are a mass of matter, they do not possess any faculty of knowing. It is the same case with material elements consisting in a living body, they have no faculty of knowing. The material elements in a dead body are like those of a living body, they are without the faculty of knowing.

Then what is that which knows the objects now? It is the element of mind, which comes into being depending on matter. It is called Name (mind) because it inclines to an object. Mind is also spoken of as “Thought” or “Consciousness”. Mind arises depending on matter as will be described hereafter. Depending on the eyes, eye consciousness (seeing) arises, depending on the ears, ear–consciousness (hearing) arises, depending on the nose, nose–consciousness (smelling) arises, depending on the tongue, tongue–consciousness (taste) arises, depending on the body, body–consciousness (sense of touch) arises. There are many kinds, either good or bad, of the sense of touch.

The senses of touch and sight are nothing but elements of the mind. There also comes into being, the mind–consciousness (i.e., thoughts, ideas, imagination, etc.) depending on the mind–base. All of these are elements of the mind. The mind as a rule knows an object which matter does not know. People generally believe that, in the case of seeing, it is the eye which actually sees. They think that seeing and the eye are one and the same thing. They also think, “Seeing is I: I see things: eye and seeing and I are one and the same person”. In actual fact this is not so. Eye is one thing and seeing is another. There is no separate entity such as “I” or “Ego” There is only the fact of “Seeing” coming into being depending on the eye.