The subtle center, bhrumadhya, textually "between the eyebrows," presents a particularly difficult passageway for the vital energy. To pass beyond it, one must have mastery over samadhi and receive the help of a very good Guru.
Verse 36 of the Vijnanabhairava deals with the practice named bhruksepa or bhruvedha, the breaking of bhru, which results in the full expansion of the energy. If at that moment the thought is free from duality, transcendence is achieved and one becomes all-pervading. One starts by filling the various centers up to the bhrumadhya with pranic energy, and then, when this center is saturated with concentrated energy and when samadhi prevents its dispersion into the outer world, one has only to slightly contract the eyebrows and project this energy immediately upon the narrow dam it has to cross in order to attain the brahmarandhra. If one is unable to channel the vital force and send it up toward the crown of the head, the breath dissipates through the nostrils. Setu is not only a dam holding in check the flow of the inhaled and exhaled breath, but also a bridge linking the center between the eyebrows with the brahmarandhra. These two centers, in the ignorant, are always unconnected, whereas in the yogin the vital force, once sublimated, crosses the bridge and reaches lalata, in the middle of the forehead. From this state—very rarely attained by a yogin—arises a diffused blissfulness and an intense heat. All functions stop as soon as bliss is enjoyed and the energy spreads inside the head, up to the thousand-spoked center; and since the ties with the samsara are broken, she changes into an energy of pure consciousness. If the term bindu is often used to designate the bhrumadhya it is because, when this center is pierced, the pent-up energy that has accumulated there is released, and a dot of dazzling light appears, "a subtle fire flashing forth as a flame." This is the "bindu," a dimensionless point—free therefore from duality—in which a maximum of power is concentrated. If the attention is focused upon it at the moment when, having reached the middle of the forehead, it dissolves, then one is absorbed in the splendor of Consciousness. The three points—the heart bindu, the bindu between the eyebrows, and the brahmarandhra bindu—have then merged into one, as they have been united by Kundalini on completion of her ascent. It is from bhru, and from there only, that the progressive attitude14 is established with its alternating phases: absorption with closed eyes and absorption with open eyes. At the beginning, when the energy rises to bhru, the breath goes out abruptly through the nose; the eyes open and one inhales; then the eyes close and Kundalini, fully erect, manifests as a tremendous flow of powerful energy. When one opens the eyes, the world fills with a new joy which produces intoxication (ghurni). When the universal Kundalini regains her spontaneous activity, one enjoys the tide of the ocean of life, with its perpetual ebb and flow of emanations and withdrawals. The yogin rests naturally in unmilanasamadhi— absorption-with-open-eyes—and enjoys the highest bliss, jagadananda. To him everything is steeped in bliss, and is nothing but bliss. 12. Through it adhahkundalini moves to the muladhara. 13. About the triangles cf. here pp. 31,33. Kundalini by Lillian Silburn
