Usually, in Zen Practice, we have to be careful of certain games the mind will play during Zazen. For example, once on the fourth day of a long and hard Sesshin, I saw a little Buddha pop out of the wall, wave to me, ask me how I was doing. We chatted mentally for several minutes, enough for me to "pinch myself", then he popped back in the wall. It is common during Sesshin, because of the strains involved, to experience such things as emotional swings, hearing becoming so sharp you can be disturbed by an ant walking across the room, strange bodily sensations such as feelings of floating or being giant sized, and paranoia. But they are usually discounted as "Makyo", defined as follows (by Daido Loori Roshi):
In Zen, hallucinations are called makyo. It is not unusual for practitioners sitting in meditation for long periods of time to experience makyo. Some people feel like they are levitating, others see visions of the Buddha bathed in light, some hear sounds or voices. This in itself is not a problem. The problem arises when we confuse these experiences with enlightenment. When students come to me in dokusan to give me elaborate description of their makyo, a common response from me could be something like, “Oh, don’t worry about it—it will go away. Maybe you’re not sitting straight.” In other words, don’t attach to it. But if a dream is real, why isn’t makyo real? Are dreams, makyo, enlightenment and delusion the same, or are they different?
In centuries past, Zen Masters used to see and hear things all the time. For example, Keizan was pretty much into things like that. Please read a couple of pages, from Page 91:
http://books.google.com/books?id=BnLOFw ... &ct=result
But, you know, that is how people thought back in the 13th and 14th century, and Keizan was particularly just that kind of person even before he started Zen practice. Heck, there are even folks now into things like that all through the Buddhist world, the Christian World, the New Age World, the world in general.