The ascetic physical regimes such as strict celibacy, total abstention from alcoholic liquor, living apart from worldly people, and not engaging in worldly business, were planned to keep the novice away from distracting environments and obstructing temptations. To concentrate successfully in meditation the mind must first become moderately settled. If it is excited with any passion, or agitated by any anger, then the aspirant finds it impossible to meditate properly. What he loves, longs for, or desires may come first before him when he sits down to meditate. The picture of that thing appears before him and makes his effort to concentrate more difficult. He may remove this unequal emphasis by strengthening his will through the deliberate renunciation of that thing for a time. This quietens the mind before he begins and thus there is a gradual, if temporary, dropping-away of the desire which might otherwise intrude and interfere. This is the theory of asceticism. Its defect is that the result is too often either a temporary repression or a total failure.
-- Notebooks Category 2: Overview of Practicies Involved > Chapter 7: Discipline Desires > # 110