from Sun, Moon and Stonehenge: pages 30 to 33

364 : The Calendrical Wonder Number

The nearest number to 365 which has a range of suitable factors is 364. The factors of this number are 2, 2, 7 and 13, and they are indeed very suitable. It is therefore not too surprising that we find that they lurk within our present 365-based calendar system. Despite the present choice of a twelve month year, we all think that there are 52 weeks in the year (4 seasons x 13 weeks), we use a seven day week and often make the assumption that there are 4 weeks in the month (4 x 7 28 days). We are taught as young children that there are 12 months in the year. This 'knowledge' takes us into dangerous waters, for the consequences of these assumptions lead to an implied year length, formed by multiplying 4 x 7 x 12, of 336 days. We are therefore missing one lunar month (29 days) by making these erroneous assumptions. The numbers here are shouting out that we need a thirteenth month and bright ten year olds with cheap calculators can work all this out. So did someone else many, many years ago, enshrining this wisdom in the world's most popular game. 

PackOfCards 364 500px

Figure 2.5. A pack of cards seen as a 364 dav calendar analogy. Black and red on a white background, these are the three colours traditionally associated with the Moon. The four suites of 13 cards has seven as the central card.

A Year of Cards