What is the Principle of Meditation ?

Three things must be present for awareness to arise - an object, the sense door and the mind. By contemplating on a single object repeatedly, (for example the breath or a visible object) the mind can be calmed and brought to one-pointedness. Similarly, many other methods of SAMATHA meditation can be found just by focusing the mind on any one object. There are 40 types of Samatha meditation. (A more detailed explanation can be found in the VISUDDHI MAGGA)