The Golden Dawn assigned the twelfth trump the letter Mem, the element Water, and the twenty-third path from Geburah to Hod. Mem is one of the three Mother letters and its element is water, which suits a card about suspension, immersion and the loss of ordinary footing. The assignment is late nineteenth century and rests on the alphabetic scheme first proposed by the Comte de Mellet in 1781 and systematised by Eliphas Levi in the 1850s.
The card is read for suspension, and the readings divide on whether the suspension is chosen. The generous reading takes it as a deliberate pause, a willingness to stop pushing, and the specific insight that comes from seeing a situation from an angle nobody else is looking from. The unsentimental reading takes it as being stuck: waiting on somebody else's decision, unable to act, and quietly paying for it.
Both are current, and a reader who only knows the generous version will misread a great many spreads, because querents who draw this card are more often trapped than enlightened. The distinguishing question is usually whether the querent chose the position, and the surrounding cards will normally say.
The sacrificial reading, something given up so that something else can happen, sits between the two and is probably the most reliable. Waite's reversed meanings run to selfishness, an unwillingness to make the sacrifice, and the crowd rather than the individual. Readers working without reversals treat a reversed card as no different and read the whole range upright, which for a card that is already upside down has a certain logic to it.