Mercury in Aquarius

Air is Mercury's triplicity by night in Lilly 1659, and Aquarius is the third air sign, so a night birth wins this entry. His list adds a face covering degrees 11 through 20 and terms from 7 to 12. Those small tallies make Aquarius one of the fuller signs in his tables for a planet with no house there.

Alan Leo 1899 offers a striking idea about the sign: fixed air, by which he means thought held still long enough to take effect. Ptolemy (Ashmand's 1822 translation) files Aquarius as fixed and says fixed signs make the mind steady and pertinacious. Mercury here is thus tied twice to steady thought in these writers.

Sepharial 1920 says Mercury takes on the character of whatever planet it aspects most closely, so the sign alone tells little. Rulership remains in dispute, since Adams 1928 gives Uranus the sign and Heindel 1919 shares it with Saturn. Modern writers usually call this placement original and unconventional, and they lean on Uranus to say so.