|The lower realm|
So what are the three realms? There are actually three different layers of these realms. The lower realm, what the Secret refers to, consists of people, events and things. Transcending this ordinary state of being occurs when one is able to see essence, or the original face. Transcendence of thought allows viewing the original face.
The middle realm is that of humanity, earth and heaven. Humanity is interposed between these entities which provide it with sustenance and inspiration. Becoming at one with these energies by clearing out our earthly vessel helps us become more healthy and allows us to consciously evolve. Qigong exercises and meditation lead one down this path.
In the upper realms, time, universe and space, the self is not separate from anything. Achieving this stage may require years of dedicated practice; and, sages who attain this level of consciousnesses are actually able to integrate the lower, middle and upper realms. This is the goal, not superseding one's earthly existence, but rather integrating all levels with one's corporeal being.
References translated by Thomas Cleary:
The Secret of the Golden Flower
Opening the Dragon Gage: The Making of a Modern Taoist Wizard