About This Teaching
A shopkeeper keeps a sharp eye on his goods when mischievous children wander in; Ajahn Chah used this to describe watching the mind with mindfulness and alertness. In another simile, the mind is like a room with a single chair. When mindfulness sits firmly on it, facing the door, every guest who enters is known at once, and with no chair to sit on, no guest stays long.
The reading notes that some practices direct thinking toward a theme of contemplation rather than a physical sensation, and that unbroken awareness there can also gather the mind into samādhi. Whatever the method, mindfulness is central, the nurse and protector of samādhi.
In his own words, mindfulness is life; lacking it is like being dead, and heedlessness robs words and actions of meaning. It must govern standing, walking, sitting and lying down, not only formal meditation. Constant care gives rise to wise shame about improper actions or speech, which strengthens restraint, and with strong restraint there is no heedlessness.