The Greater Holy Assembly (Idra Rabba Qadisha) 6

58IN the hollow of the skull is the aérial membrane of the supreme hidden Wisdom, which is nowhere disclosed; and it is not found, and it is not opened.

59And that membrane enshroudeth the brain of the hidden Wisdom, and therefore is that Wisdom covered, because it is not opened through that membrane.

60And that brain, which is itself the hidden Wisdom, is silent and remaineth tranquil in its place, like good wine upon its lees.

61And this is that which they say:—Hidden is the science of the Ancient One, and His brain is calm and concealed.

62And that membrane hath an outlet towards Microprosopus, and on that account is His brain extended, and goeth forth by thirty and two paths.

63This is that same thing which is written: “And a river went forth out of Eden” (Gen. ii. 7). But for what reason? Because the membrane is (then) opened, neither doth it (completely) enshroud the brain.

64Nevertheless the membrane is opened from below. And this is that which we have said: Among the signatures of the letters (is) ThV, Tau, Th; nevertheless He impresseth it as the sign of the Ancient of Days, from Whom dependeth the perfection of knowledge, because He is perfect on every side, and hidden, and tranquil, and silent, like as good wine upon its lees.