The first phase is to learn how to collect his forces together and pin them down to a particular theme, thought, or thing. It is essentially an exercise in attention and concentration. This is attempted daily. To succeed in it he must exert his power of will, must adopt a determined posture, or the mind will wander off repeatedly. With enough work on this phase he will be able to begin meditation proper, for which this was only a preparation.
-- Notebooks Category 4: Elementary Meditation > Chapter 1: Preparatory > # 220