Celestial Mem is drawn as a glyph-form for the Hebrew letter Mem 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; Mem's own sound and classification, discussed elsewhere in this atlas, belong to the underlying Hebrew tradition.
As one of the Sefer Yetzirah's three mother letters, Mem is paired with the element water and, in the same classical scheme, with the belly and a cold climate, the belly being read as the seat of silence and stillness, the passive counterpart to Aleph's breath and Shin's speech. 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. Of the other two mother letters, Aleph is paired with air and Shin with fire, the three together forming the elemental triad the Sefer Yetzirah builds its whole cosmology upon.