"Straight is the way and narrow the gate thereof" said Jesus. The Hindu Upanishads, the sacred and formerly secret works containing some of the highest wisdom of India, have a similar phrase: "The path which is as narrow as the edge of a razor." What do these words mean? They do not tell of a path to moral perfection, however desirable it may be to be morally perfect. No! the way they speak of is the Ultimate Path which demands from us utter and complete rectitude of thought and feeling. Every movement made in the heart and mind must be completely straight, undeflected, and undistorted. The mental activity must be true in every sense of the word. Life must become one-pointed, perfectly concentrated, moving always in a straight line. When ideas are warped by prejudices, or distorted by preconceptions, or clouded by illusions, or inflamed by excitements, then the movement of the mind is not straight but wavering from side to side. It may even turn round and move backwards. We inevitably approach life with a predetermined outlook which has gradually developed from the many influences played upon us since childhood. Rare indeed is the man who is immune to them. This bias tends to overload with personal feeling all judgement, and to raise selfish emotion to the status of a test of truth.
-- Notebooks Category 2: Overview of Practicies Involved > Chapter 6: Self-Reflection and Action > # 20