There remains one minor aspect of his work which must be briefly examined, because it has become closely associated with his name.  This is his number-symbolism, by which he ascribes important powers to certain numbers, so that they are regarded as holy themselves and sanctifying that to which they are attached.  This feature of his thought is commonly ascribed to Pythagorean influence, which was strong at Alexandria, and, indeed, throughout the world, at this era.  The exact details of the holiness of four, seven, ten, fifty, etc., Philo may have borrowed from neo-Pythagorean sources, but the general tendency was the natural result of his environment and his stage of thought.  It was a feature of the recurring childishness of ideas and the renascence of wonder at common things which is apparent on many hands.  To have denied the powers of numbers would have seemed as absurd and eccentric then as to deny the powers of electricity to-day.  And in all ages people have been found to regard numbers mystically as a link between God and earth, and a means of solving all physical and metaphysical problems.  The Hebrew intellect, primitive as it was, tended particularly to the reverence of the numerical powers.  Witness the Bible itself, which emphasizes certain numbers; and witness also the fifth chapter of the Pirke Abot, with its lists ranged under four, seven, and ten, which is only typical of the rabbinical attitude.  Philo is not original in his views concerning numbers, not above nor below the loose thinking of his age.  He accepts unquestioningly the potency of seven, because of its marvellous mathematical properties, ratios, etc., its geometrical efficacy, and because of the seven periods of life from infancy to old age, of the seven parts of the body, the seven motions, the seven strings of the lyre, the seven vowels, and the very name, which is connected with worship ([Greek:  sebasmos]).  All this is trifling and trite, but what is of importance is the use which Philo makes of the sentiment.  He converts it throughout to the support and glorification of Jewish institutions.  Thus, if a man honors seven, he says, he will devote the Sabbath to meditation and philosophy.[276] Further, as seven is the symbol of rest and tranquillity, the Sabbath must be a day of perfect rest.  Ten is magnified so as to honor the Decalogue,[277] fifty so as to honor the Feast of Pentecost.  So, too, the Pythagoreans’ mathematical conceptions of God as “the beginning and limit of all things,” or, again, as the principle of equality, are approved by Philo, “because they breed in the soul the fairest and most nourishing fruit—­piety.”  In short, Philo’s Pythagoreanism only emphasizes his commanding purpose—­to deepen and recommend the Jewish God-idea and the Jewish method of life.