One property of any substance that alters consciousness is that it offers access to another side of one’s awareness. That’s the whole point, right? Whether you’re having a glass or two of wine, a bong hit, eating a mushroom, or taking an ayahuasca journey, the idea is to feel different.
Yet more than that is involved, especially if the consciousness-altering substance is used to access that side of awareness on a regular basis. What happens is that consciousness can bifurcate, with ‘normal’ consciousness on one side and the ‘other state’ on the other side.
What can happen then is that not just two states of consciousness emerge, but rather two different personalities, with different properties. A person might be attracted to certain people or experiences, but only from one of the personalities. The two sides of the psyche might be aware of one another’s existence but not seem available from the other when one or the other is in action.
You might learn distinct things and bring them back, or return a "changed person." The effect might be part of what many people experience as the mind/body split—their body wants things that their mind is too rigid to allow. In extreme situations, the two sides might not be aware of one another’s existence, such as when one has a blackout experience under the influence of alcohol and does not remember what happened.
In whatever form this takes, I call it the hemisphere effect, because it involves such distinct aspects of consciousness. Another way this might manifest is when you’re involved with another person who is accessing consciousness this way; you are in relationship to both (or additional) hemispheres. In any event, there is a need for integration of these aspects of the psyche.
Yesterday’s Gemini New Moon was exactly square Neptune in Pisces. This is like an enforced meeting between the two most dualistic signs—Gemini and Pisces.
It’s almost as if you took half each of each side of Gemini and Pisces and merged it with the other. There is a confrontation where the two aspects of the psyche are being compelled to engage with their counterparts, not of their own sign—of their fellow mutable sign. There are aspects (to minor planets in the pattern) that indicate this is not merely a meeting, but rather it’s precipitating integration of the seeming pairs of opposites.
Note that as this happens to you, you may choose to make decisions or to take action; this would start with observations that have a way of snowballing in momentum. That is what integration of the psyche is all about: You become more distinctly you, in the whole sense, and able to act that way: with integrity.