Dennis Genpo Merzel, Roshi was my Zen teacher for over twenty years. He created a technique, derived from the therapy known as Voice Dialogue, called the Big Mind process, which I first experienced in 2000 at a sesshin in Wales. I subsequently went to Salt Lake City in Utah, where he was based at that time, to learn it for myself. I have been using it ever since; when I was a therapist, I used it to complement my Cognitive Behavioural Therapy (CBT), and I incorporated it into my version of the eight-week Mindfulness Based Stress Reduction course. But I have also made it available to our sangha, and included it as a voluntary option on sesshins (retreats).
Essentially, on a day-to-day basis, we're all run by committee: various parts compete for dominance of the mental air-time, and they don't always get on! The worker, the spouse, the layabout, the angry one and so on. Also there are parts which we have difficulty owning: they tend to get stuck in the basement and don't get a say. So far this is Voice Dialogue. But Genpo realised that, once you had an effective method of shifting from part to part, then you could use that to access some of the meditation states that would not normally be accessible until you had done years of practice. And so it has proved. The parts known as Big Mind, Big Heart, Non-seeking mind, and Great Intimacy are some that become available in this process.
This can also be really encouraging for your sitting practice, so you no longer need to rely 100% on blind faith that this Zen practice is transformative. But it's also useful to get in touch with those ‘disowned’ parts and let them out of the basement. In this way we can avoid what has become known as ‘spiritual bypassing’ which is an undesirable if tempting tendency!