Mercury in Libra

Lilly 1659 urges the student to watch Mercury above all the planets, because it partakes of the influence of any planet it aspects: heavier with Saturn, he says, and more jesting with Venus. In Libra it sits in Venus's chief house and in one of the air signs, which he hands to Mercury by night. A birth after sunset gets that triplicity in his reckoning and a birth by day does not.

His terms reach only five degrees here, the twentieth through the twenty-fourth, the narrowest slice he allots Mercury in any sign. That is a quirk of the table with nothing further claimed for it. Ptolemy (Ashmand's 1822 translation) leaves this sign's equinoctial class out of his chapter on the mind.

Alan Leo 1899 describes Libra as comparing and weighing, a habit that fits Mercury if reason is understood as sifting. Modern writing describes a diplomatic thinker here, and the description is modern.