Part III: The Circumference and the Hieroglyphic Monad in In Operibus Sigillo Dei Aemeth by David Richard Jones.

“In the context of Liber Secundus, 4T may be said to represent the Tetragrammaton. T for Tetragrammaton and 4 indicating its meaning the four lettered name, that is הוהי, Yahweh or Jehovah, the demiurge, God the father and the key of Qabalistic formulae.” [via]