Beyond the festivals, twenty-five functions chiefly as a threshold of maturity or completion. In the priestly law of Numbers the Levites begin their service at twenty-five, and the quarter-century remains the natural unit for marking anniversaries and generations. Modern numerology, following the reduction of twenty-five to seven, reads the number as a call to inward analysis and learning through experience, the seven arrived at by way of the doubled five of restless change, a reading that belongs to the twentieth-century American system rather than to any older source. The durable content of twenty-five is calendrical and commemorative: the date of Hanukkah, the traditional date of Christmas, and the silver jubilee, rather than any deep body of lore.
Walter Burkert's study of the Pythagorean tradition finds that the ancient arithmological reading of the small numbers, one as source, two as division, four as justice and so on, reaches modern readers through Neopythagorean writers of the centuries after Plato rather than from Pythagoras himself; twenty-five, as five multiplied by itself, would on that older logic read as an intensified five, the number the Neopythagoreans associated with marriage and with change, a reading distinct from, and considerably less developed than, Balliett's own twentieth-century American system.