J was not a separate letter of the Latin alphabet Trithemius was ciphering in 1518, and the earliest Theban sets carry no sign for it: the sign for I served for both. The Theban J in circulation today is a later supplement, usually described as adapted from the I, but nobody has identified the chart or edition in which it first appears, or the hand that made it. The modern twenty six letter Theban set therefore contains one letter with no traceable origin at all.
What would resolve this A bibliographic collation of printed Theban charts in sequence, from Polygraphiae in 1518 and Agrippa's De occulta philosophia in 1533, through the eighteenth and nineteenth century grimoire reprints, to the twentieth century witchcraft revival, to locate the earliest surviving witness of the supplementary sign and to name the edition that introduced it.
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