Celestial Ayin is drawn as a glyph-form for the Hebrew letter Ayin in the Alphabetum Coeleste, one of three magical scripts Heinrich Cornelius Agrippa published in 1533, its strokes tipped with small circles in imitation of star charts, rather than a script with independent letter meanings of its own; Ayin's own sound and classification, discussed elsewhere in this atlas, belong to the underlying Hebrew tradition. As one of the Sefer Yetzirah's twelve simple letters, Ayin is assigned to the zodiac sign Capricorn and the Hebrew month of Tevet, and, in the same classical scheme, to the faculty of mirth.
Agrippa printed Celestial alongside Malachim and Passing the River in Book III of his Three Books of Occult Philosophy, Cologne 1533, without citing a source for any of the three, and no earlier witness to any of them survives; historians generally read the scripts as a Christian Kabbalist's own reworking of Hebrew letters into star-chart-like glyphs for use on talismans and amulets, most likely Agrippa's own invention following Johannes Reuchlin's earlier Christian engagement with Hebrew letter mysticism a generation before. That zodiacal and monthly assignment, like Ayin's meaning, eye, belongs to the underlying Hebrew letter rather than to this particular Renaissance glyph-set, which simply reproduces it in a different hand.