It's the realization of the relative insignificance of people we come in contact with, in contrast to their entire all consuming reality (and vice versa), which is the head trip. Not just wondering what they are thinking or how they process things, but realizing that there is someone whose reality is as significant and all consuming to them as my reality is to me, yet it is entirely different from mine. Also, maybe that we cannot truly experience or appreciate each others' realities.
