I've often likened spiritual practice to the setting up of a feedback loop, in quite the same way that one can do with a video camera or a microphone.
To create a feedback loop with a camera, you connect the camera to a monitor while pointing the camera at it. What happens then, is that the signal that is being recorded is simultaneously emitted on the screen. At first you will see replicas of the screen inside one another, but with some gentle movements you can begin to interfere with the image until it breaks down into patterns of color and form and if you hit the right spot everything dissolves into a pure white light. Similarly with a microphone, if you bring a microphone which is recording close to a speaker which is emitting what is being recorded, it begins to resonate and produces a high pitched ringing sound (which if you aren't careful can blow the speaker).
So likewise, the aim of most genuine spiritual practices, is to know the knower, see the seer, to place awareness on awareness. If you can succeed in doing this with sufficient intensity and for long enough, what happens is that something 'breaks', there is a shift into a non-conceptual mode of awareness. At first you may perceive all sorts of phenomena, somatic vibrations and sensations throughout the bodily form, visual displays of color and pattern, emotions both euphoric and terrifying or seemingly endless mazes of thought forms; but passing through all of this, and allowing awareness to finally rest in it's own nature one reaches that fullness which the tantric tradition termed Bhairava; beyond what can be known with the mind or through the senses; paradoxical and ineffable.
This process of unfolding, or ascending from the contraction of limited individualized awareness towards the fullness of universality is known as the rising of Kundalini