Why is seven *the* magical/ mystical/ mythical number? Geoffrey Ashe's answer...

I have previously written about the strange way that things fall into sevens; but it is also well known that seven is usually primary in a most (although not all) magical, mystical and mythical contexts - dating back to Medieval times, and far more anciently. 

Seven has some interesting properties arithmetically, and is notoriously difficult for children to handle, when it comes to times-tables and mental arithmetic - but these aspect of the number are hardly mystical. 

And the psychological origins of this primacy of seven is very difficult to explain, because there aren't any very obvious sevens in nature. 

Indeed, the seven-ness of things is often attributed rather than actual - as with the (supposedly, but not really) seven stars in the Pleiades, the colours of the rainbow, and the "planets"*...

(*To make seven planets required leaving-out the earth, and instead including the sun and moon; until, eventually, Uranus was discovered.)  

Furthermore, there are exceptions to the primacy of seven - so that any explanation of its role must take these into account. 

A few weeks ago I discovered a book that tackled this seven business head-on, analysed the phenomenon in great detail; and offered a plausible and coherent explanation: it is The Ancient Wisdom by Geoffrey Ashe (1977). 

Ashe's answer (as some will have guessed from the illustration) is that the number seven derives its importance from the stars of the most obvious and recognizable of all constellations of the Northern Hemisphere; known at the Plough, Big Dipper, Great Bear and Arthur's Wain - which has been used for a long time** to find the North Star - Polaris. 

(**If you go back far enough, Polaris was not always close enough to true north to be a useful guide; and it will not always remain where it now is - axial precession.)

Geoffrey Ashe's argument is too long, complex, and nuanced to summarize - but it convinced me! 

If you are interested in the origins of magic seven - you now know where to look.