Robert A Rosenberg writes:
<begin snippet>
It is not as simple as that since you have to allow for calenders getting out
of sync. When the Julian calender was replaced by the regorian one, there were
(depending on where you were since the
switch occurred in different years in different countries) 13 or so days lost.
</end snippet>
thus inadvertently proving my point. No days were lost. The Roman calendar
was not replaced by the Gregorian calendar. The new Gregorian calendar simply
became the official civil and religious calendar in some jurisdictions (at
different times) The Roman calendar did not cease to exist. It indeed
continues in use: The Orthodox Church still fixes the date of Easter in it.
Many calendars coexist at any point in time, and so-called proleptic dates,
which fall before the epoch origin of some calendar, can always be assigned
earlier events in that calendar. (One can, for example, date the assassination
of Julius Caesar in the French Revolutionary Calendar, the epoch origin of
which is 1792 September 22 in the Gregorian calendar and 1792 September 11 in
the Roman calendar.)
Mr. Rosenberg, an able man who makes valuable contributions to this forum, has
thus convicted himself out of his own mouth of knowing very little about
calendars. Worse, much of what he thinks he knows is, as is often the case,
wrong. Even worse, he has not though it necessary or even desirable to think
at all hard about these questions. If he had he would not be retailing the
absurd notion of lost days.
Christoph Clavius's definitive treatment of the Gregorian calendar is,
regrettably, in untranslated Latin; and this makes it inaccessible to Latin
dropouts. The standard modern reference, which I have cited here before, is
Dershowitz, Nachum, and Edward M. Reingold, Calendrical calculations,
Cambridge: Cambridge University Press, 1997. Their book is in accessible
modern English, and it were better to read it carefully and to study the LISP
routines it contains with attention before pontificating about dates and
calendars.
John Gilmore Ashland, MA 01721-1817 USA
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