The Key is card number 33 of the Petit Lenormand, the thirty-six card deck read in the nineteenth-century French cartomantic tradition that took its name, after her death in 1843, from the Parisian fortune-teller Marie Anne Lenormand.
Image, meaning and playing card
The card shows a key. In the tradition its core sense is solution, certainty and opening; an emphatic card of yes, of destiny and of doors unlocked.
Like every card in the deck it also carries an inset playing card, here the 8 of Diamonds, a survival of the ordinary piquet pack over which the pictorial Lenormand was laid. Lenormand cards are read less as standing symbols than in combination, each modifying the cards to either side, so that the key takes much of its final meaning from its neighbours in the line or the Grand Tableau.
In the original German tradition the card is Der Schluessel. As House 33 in the Grand Tableau, any card landing in that numbered position is read as touching on solutions, certainty and the definite opening or resolution of a matter. In combination, Key followed by Fish reads as a solution to a financial question or the definite arrival of money, while Key preceding Mountain reads as an obstacle about to be resolved or unlocked. The card is conventionally read as one of the more emphatic in the deck, since its core sense of certainty tends to strengthen or confirm whatever quality its neighbouring card carries rather than modifying it ambiguously.