Another very interesting exercise to awaken the telepathic plexus is as follows: the disciple should sit down on a comfortable chair with his sight toward the East. Imagine that in the East there is a great golden cross that emits golden and blue rays. The disciple will imagine those rays entering through his solar plexus to awaken it and give life to it.
This exercise is practiced ten minutes daily.
This exercise is always practiced in the first hours of the morning, that is, at dawn.
The chakra of the solar plexus collects the solar energies and with them nourishes and develops the other chakras of our astral organism.
Whoever develops this chakra acquires the great power of telepathy.
The syllable UN, extending the sound over the letters U and N [the U is pronounced like OOO], can be vocalized during the practice of the golden cross at dawn.
The solar plexus is our receiving antenna, and our pineal gland is our emitting center.
Samael Aun Weor
Manual of Practical Magic, chapter 3