The wise silence of the lips is the first door into the Jerusalem of the mind or the watchfulness of the mind, even though the mind itself is not yet silent. The second door is temperate moderation in eating, drinking, and sleeping. The third door, which purifies the mind and the body, is the constant remembrance of and reflection on death (Text 6).
Cleary, Thomas. The Way of a Pilgrim and The Pilgrim Continues His Way . Shambhala. Kindle Edition.