Most historical calendars have been abstractions of the major observable astronomical cycles, especially the sun and moon. Widely different cultures often wind up with similar looking calendars, and at first sight it might seem as if direct influence were involved. While such may have been the case in certain instances, the conclusion is not necessary. If we consider the problem from the point of view of a hypothetical calendar designer, the possible calendars we can design are heavily determined both by the nature of the observed cycles and by the needs of our society. So what possibilities does our calendar designer have?

This program generates a Christian ecclesiastical calendar for any year you select. It will calculate the dates for the moveable feasts based on Easter (Ash Wednesday, Pentecost, etc.), Advent, and many saint and other feast days. The calendar filters holidays by date and locale.

To navigate in the calendar, you can click on the buttons beneath the grid display, which will scroll one unit at a time. Alternately, you can select the month by pulling down the choice box, or the year by clicking on the year box and editing it to the desired year (you need to hit the "enter" key for the year to change in the calendar grid). The calendar will correctly display BCE dates, but because of the year filtering, no holidays will appear in the list box.

The following article is adapted from a longer series of posts that I originally wrote for the Historical Writing section of Compuserve's Literary Forum in 1996. (The Literary Forum still exists under the name "Books and Writers Community", but its structure has radically changed, so most of the old sections are defunct.) I wrote the original in response to a skeptic (that's the polite word) who proposed the theory that conventional historians had grossly mistaken the chronology of both the ancient world and the Middle Ages. In the original piece, I tried to explain how historians piece together different facts to arrive at a chronology.