yeah when you start thinking of things in terms of lighter and darker, it gets too easy to polarise everything you come across. i prefer to see things as more or less physical, and dark work definitely blurs the line between what we would consider physical reality and the astral.
what i found when i got to the end of one session of dark visualisation was that the room would pulsate and sway with invisible currents much like seaweed under water. it’s hard to explain but it’s a lot like watching a documentary on coral or something. it’s that undulating, waving kind of flow, but it’s moving the darkness of the room itself. right after that the mist appears everywhere, then colours, double-images of objects in the astral etc, but the astral is always moving.
it’s incredibly hard to explain but once you see it, you’ll never forget and you can always call it up in ritual once you reach trance. it’s a receptive state, though, and you have little control over anythig. the opposite is true of light meditations, but you tend to see the astral less, and higher vibrations more. similarly, you can implement your Will using light but you become naturally less receptive to what’s going on around you in the astral.
i guess you could say dark meditation makes your third eye more receptive (left hand), while light meditation makes it more projective (right hand). obviously, receptivity is best for crying, divination, communication etc, while projectivity is better for casting circles, opening gates and raising energy.
both are great, but very different.
hope i didn’t confuse you more…