One of the great remedies for conquering fear is to face boldly what one fears. You are put face to face with the danger you fear and you fear it no longer. The fear disappears. From the yogic point of view, the point of view of discipline, this is the cure recommended. In the ancient initiations, especially in Egypt, in order to practise occultism, as I was telling you last time, it was necessary to abolish the fear of death completely.
Well, one of the practices of those days was to lay the neophyte in a sarcophagus and leave him in there for a few days, as though he were dead. Naturally, he was not left to die, neither of hunger nor suffocation, but still he remained lying there as though he were dead. It seems that cures you of all fear. When fear comes, if one succeeds in putting upon it consciousness, knowledge, force, light, one can cure it altogether.
Ref: Questions and Answers 1954