The article, “At Least Noah Had Some Warning,” by Wendell Duffield (Eos, July 10, 2001) provides a fascinating story, but suffers from a malady common to many publications dealing with historic events. The terms “Anno Domini” or the abbreviation A.D.,and the corresponding “Before Christ” or B.C., refer to a calendar in common use across global cultures, but these particular terms specifically reflect events that are only of significance to Christian cultures. The “Domini” in “A.D.” may be the author's lord, but it is not mine, and it certainly was not Tlachoc's either.There is a parallel usage, which lacks the specific religious connotation of A.D. and B.C. .The terms Common Era and Before the Common Era, and the abbreviations CE and BCE, refer to the adoption of the Julian/Gregorian calendar's zero year as a common benchmark in history rather than to its religious connotations. (This is actually a simplification. For a more detailed discussion, go to http://serendipity.magnet.cn/hermetic/cal_stud/cal_art.htm#Astronomical).