Chronograms and the Science of Letters

One of the abjad system's most distinctive uses is the chronogram, a phrase or line of verse composed so that the sum of its letter values equals a particular year, most often the year of a building's completion, a ruler's accession or a notable death. Composing a chronogram that reads sensibly as a sentence while also summing to the correct date was a genuine literary art across the Persianate and Arabic speaking worlds, and inscriptions built this way still appear over gateways and on tombstones from Ottoman Istanbul to Mughal India.

Abjad numerals also underlie ilm al-huruf, the science of letters, a current within Islamic esoteric thought that treated the Arabic alphabet, its numeric values and the combinatorial possibilities between letters as a key to hidden properties of language, nature and the divine names, a strand of speculation connected to the wider tradition of Arabic occult science that also produced influential work on alchemy and natural magic. As with the comparable Jewish and Greek letter-number traditions, the arithmetic itself is straightforward and well documented; the interpretive claims built on top of it, about what any particular total is supposed to mean, belong to the specific school or author who advanced them rather than to a single unified doctrine.