In Gregorian and Julian Calendars, every date on a whole year or on the two parts of a leap year gets a weekday connected to other dates that year / part of leap year.
This is possible because lunar months are eliminated, all months have standardised day numbers. When lunar months really are lunar, you don't know the weekdays of the dates until the month arrives, but this is not our case. February some years gets a day extra, we know which years, and it is the only month which varies in length. So, it os possible.
It is also interesting because the Sunday letter shifts from year to year, and at leap day in leap years. In a year with 364 days, the Sunday letter would be the same every year. 350 = 7*50, 14 = 7*2, 350+14=364.
But Julian and Gregorian calendars are about a year with 365.25 or 365.2425 days, not 364. So, some years have 365 days and the last day, December 31, has same Sunday letter and Week day as the first, January 1 had had. But this December 31 is also followed by January 1 of next year, which therefore has on each Sunday letter (starting with A on January 1) one weekday later than the year before. In leap years, when the similar shift occors on leap day too, December 31 is however 366th day, and will have its A already one weekday later than January 1, so the ensuing January 1 will be two weekdays later than the one at beginning of the leap year.
One can also put it this way : which Sunday letter will Sunday be on?
A - January 1, like years beginning on Sunday?
B - January 2, like years beginning on Saturday?
C - January 3, like years beginning on Friday?
D - January 4, like years beginning on Thursday?
E - January 5, like years beginning on Wednesday?
F - January 6, like years beginning on Tuesday?
G - January 7, like years beginning on Monday?
Obviously, if Sunday letters went forward each year, January 1 would next year be falling on previous weekday, it is not the case, it would be the case with a year of 363 days.
This means, Sunday letters are instead going backwards.
And since this year is Sunday letter A, previous leap year was Sunday letters C and B. 2015 was Sunday letter D.
And after I tell you how I checked, I will tell you why this is relevant for Creationism.
It is already some way into the year. You can't recall what weekday New Year's Day was on. How do you check the Sunday letter?
Well, you pick up the latest newspaper, ideally daily, you can lay hands on. I am not doing it, but if I were, I guess from computer I would be getting May 19 as a Friday. The above means, every year (or second part of leap year) when May 19 is a Friday should be Sunday letter A. Is this true?
Well, first of all, we look at Sunday letters within a month, how they relate. Not specifically "A", but since the months start on different Sunday letters (some repeating), "n" and then n+1 - n+6.
In the case of February 29th on a leap year, it is actually same Sunday letter as February 28th a normal year. But all other 11 29ths of the month have same Sunday letter as 1st of same month.
Now, how do we know which Sunday letter the first of a month is? January is A, obviously, but then?
January 29 - A
January 30 - B
January 31 - C
February 1 - D
So February is D, shall we go on? No, it would be tedious. The result is already known, you can check it for yourself with some patience. But the already known fact has already been set in memory verse. In Swedish it is:
Alla De Dagar Gud Böd Eder Gå, Christeligen Fram Att Dem Fullborda
If I can goof around with English a bit, as with "go" instead of "walk", and "dem" instead of both "the" and "them", and especially radically replacing "ye" with "ee" here we have a translation:
All Dem Days God Bade Ee Go Christianly Forth As Dem Fulfilling.
Is it true that December 1 is Sunday letter F? Well, December 31 is supposed to be A, it is supposed to be N+2, and FGA means this is F.
May is 5th month, take 5 words:
All Dem Days God Bade ...
So, May 1 is Sunday letter B, and May 19 like May 5 is B+4, BCDEF, it's an F today. But B+6 is not "H" - a Sunday letter not existing, but A. So, the Sunday letter for 2017 is A.
Now you will want to know how this relates to Creationism?
Well, we know the weekdays of the days of Creation : Sunday to Friday were the six days of new creatures being made, Sabbath was the seventh day, on which God was only blessing the types already made.
What if we also knew the year and the date?
Well, Patristics both East and West of 1054 do claim man was created on March 25, so Friday March 25 in Creation year corresponds perfectly to Good Friday March 25 on which Christ died for us.
What does March 25 as a Friday imply? 25 of a month is N+3. March 1 = D. D+3 = DEFG. Friday G. And that means Sunday is B, since G+2 = GAB = B.
And this brings us to the years calculated in diverse chronologies!
Here we have been discussing the carbonic implications of Syncellus (differing 8 years from normal Byzantine liturgic chronology, Christ born 5500 AM instead of 5508 AM), of St Jerome even more often (Christ born 5199 AM) and I was testing carbonc implications of Ussher (Christ born 4004 AM) and of Jewish calendar (in which 5777 overlaps with 2017).
So, how about testing the Sunday letter implications of them?
I'll be back.
Hans Georg Lundahl
St Celestine V*
* Natalis sancti Petri de Morono Confessoris, qui, ex Anachoreta Summus Pontifex creatus, dictus est Caelestinus Quintus. Sed Pontificatu se postmodum abdicavit, et in solitudine religiosam vitam agens, virtutibus et miraculis clarus, migravit ad Dominum.