Thank you, and you raise good points. As to the first point, you are correct, and there is no stigma meant or implied in any way for someone who has a medical/psychological condition or who has been a victim of trauma. I just don't know how to describe such situations without using those terms however, but no stigma was implied.
As to the second, what you say is true. However, if the person is cautioned to take a break or stop if they feel more disquiet or difficulty than they feel that they can handle, and to discuss it with their Zen teacher, then it should not be a serious event. I have had a relatively small number of people come to me sometimes who find the quiet or loss of "self" disturbing, but after we discuss it, they either go back later because it was just a passing moment, or they decide that Zazen is not for them. While there may be someone who is truly terrorized, I would imagine that it is rare. In fact, I would imagine that someone would be much more terrorized in their feelings by, for example, getting on a roller coaster at an amusement park heading for that first big drop, hearing a strange "bump in the night" in their house at midnight, or imagining "worst case scenarios" when going to a doctor's office for a test. Many things in life can cause fear. In fact, Zazen is a practice which helps us reduce fear in meeting those other situations in life (at least for me, as I could never set foot on a roller coaster until I began to practice Zazen, and likewise for my state of mind when I undergo medical tests!
However, for a "Bump in the night," I still get under the bed, and send my wife out with a baseball bat.
)
Sorry to run long in my words.
Gassho, J
STLah