Catholic dealing of days

So this question is based on something I heard that might be incorrect. I heard that in Canon Law which deals with certain days, unless the specific law states otherwise, the day begins at local midnight.

Why would Catholic law treat days in this way, seeing as by the Jewish reckoning, a new day begins at sundown, which is based on the wording of Genesis, which both religions share?

I am also pretty sure that some holy days use the old reckoning (I think things like lent end at sundown on Good Friday or something similar?). So seeing as most, or at least many of the first Christians were Jews, at what point did the church change from considering days to begin at sundown, and say that days now begin at some arbitrary point in the middle of the night?

Correct. A day is 24 hours from midnight to midnight.

Because we aren’t Jewish and Jewish ceremonial law has nothing to do with Catholic ecclesial law.

No. The day is still midnight to midnight.

Certain liturgical functions happen at various times, but they have nothing to do with the Jewish reckoning of time.

The Church in the Bible begins celebrating together “on the Lord’s Day”. The resurrection happened on Easter morning, therefore vigils took on a specific character of awaiting the Lord. Vigils took place at night with the Eucharist celebrated after midnight and in the morning/day.

Midnight to midnight reckoning of time is a Roman civil demarcation that the Church adopted. The liturgy of the hours take their name from the Roman clock.

The Church adopted the Roman civil calendar and method of reckoning time in the first century.


There’s nothing arbitrary about midnight. Astronomical midnight cuts the night exactly in half, and time zones are designed to try to get the clock’s midnight close to astronomical midnight, while still allowing large geographical areas to all use the same clock. Sure our convention more closely resembles Roman practice than Jewish practice (you know, we’re Latin Rite Catholics, not Jews), but there’s nothing arbitrary about it.

I know this wasn’t your main point, but the others have addressed that. To answer your tangential example here, Lent ends at the Mass of the Lord’s Supper on Holy Thursday, fwiw.

Day and celebration have a distinction. Some celebrations may begin in the prior day (midnight to midnight).

If astronomical midnight is actually the middle of the night, it would have to be a shifting time, since the time the sun rises and sets constantly changes. I don’t see how time zones would account for that, at least not in a very exact manner. Since it’s always at 12am there is definitely an arbitrary aspect to it. But regardless that wasn’t really what I was talking about.

I mean that let’s say astronomical midnight was always at exactly 12am. I’m saying the middle of the night doesn’t make any more logical sense as the start of a new day than say, high noon. Or three quarters into the day. Or at the end of the night. A day is a revolution of the Earth, so just picking one point on the circle and saying “this is the starting point” seems arbitrary to me.

At the very least using sunrise or sunset to define the beginning and ending of a day seems slightly more objective and logical, since sunset is the objective end of the day in the colloquial use of the word.

I disagree. It’s still light out for at least an hour after sunset. So I don’t think the day ends at sunset.

And like I said, cutting something in half isn’t arbitrary, it’s one of the most intuitive things to do. If two people want one cookie, the only thing to do that wouldn’t be arbitrary is to cut it in half. Thus we cut the night in half, since it doesn’t make sense to end the day when it’s still light out.

And of course the real answer to your question is still that we are Latin Rite Catholics, so Roman traditions and customs are part of our heritage.

Lent officially ends on the evening of Holy Thursday, when the Mass of the Lord’s Supper, including the foot-washing ceremony, begins. Is this a carryover from the Jewish calendar? I suppose that is at least a possibility, but it isn’t something that can be known for certain.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit