Every other detail of TM is negotiable and this one is not. The instruction is that the mantra is thought without effort, allowed to become fainter, allowed to disappear, and picked up again without irritation when the meditator notices they have been thinking about lunch. Teachers spend most of the four-day course correcting people who are trying. The organisation describes the resulting state as restful alertness and points to a large literature on physiological correlates; that literature is uneven and much of it comes from institutions the movement founded, which critics note and which the movement does not deny. What is not disputed is that TM is easier to keep up than most techniques, which may be the whole of its advantage.