Those who want to learn how to go out in the astral body at will; those who want to enter the Jinn science to learn how to get into the fourth dimension with their physical body and to transport themselves with their physical body, without the need of an airplane, to any place in the world; those who urgently need clairvoyance and clairaudience, should concentrate their mind daily on the heart chakra and meditate deeply on that wonderful center. A daily hour of meditation in this center is wonderful. The mantra of this chakra is the vowel O, which is vocalized by prolonging the sound, like this: OOOOOOO.
We must pray to the Christ asking during the practice indicated here that he awakens our heart chakra.
Samael Aun Weor
The Perfect Matrimony, chapter 17