ON THE VALUE AND MEANING OF PROCLUS’ PERFECT YEAR

Abstract

An 18-digit number for the length of the Perfect Year was given by Proclus in his commentary on Plato’s “Republic”. The number was corrupted in the manuscript tradition and now it is known up to some missing and uncertain digits. Previous attempts to reconstruct Proclus’ value as a multiple of planetary periods known in ancient Babylon and Egypt led to number which has nothing in common in its writing with the one of Proclus, except the scale. Our approach to finding the original Proclus’ value is based on the assumptions that it should include as multiples some of Babylonian and Egyptian planetary periods and that the other prime factors should be of same (or at least comparable) scale as the planetary periods, known to the ancients. The value could contain also other periods, in particular, of Greek origin. After careful examination of all possible candidate numbers for the original Proclus’ value of the Perfect Year only one among them is shown to satisfy the assumptions. At least one of them can be related also to metaphysical concept (the significance assigned to amicable numbers 220 and 284 by the Pythagorean tradition), which is in agreement with Proclus’ method to calculate the Perfect Number. Another multiple, with difference of one year, appears as time interval, derived from the Turin Royal Canon, including its mythological columns, which may be also considered as confirmation of its significance for the ancient astronomers.