Great Doubt
During the Big Mind process, we can experience directly - although only as a shadow of the full-blown experience - Big Mind. The reaction seems to often be one of Yes, this looks like what the different teachers and mystics describe, but it seems so simple!
This can bring up what Zen calls Great Doubt, and motivates us to clarify the experience and the nature of mind/existence through sitting practice. Can it really be so simple? I'll have to explore it fully, with my whole body/mind, my whole life.