Excerpt from Dark Days Tarot Guidebook by Emily Mundy:
0. The Fool~
The Fool, the card with the number zero and an elemental correspondence to air, symbolizes the seemingly “foolish” attitude of positivity, playfulness, and indulgence in the odd. A creature of universal love and non-limitation, The Fool chooses to infiltrate the realm of the senses, and to stir a joyful, joking-sort of wisdom into the seriousness of practical situations. The Fool from the upside-down is careless, and underestimates the severity and importance of the current situation. A degree of seriousness is necessary for the safety of the body and soul.
upright: entrance; attitude of kindness, love, and positivity
right: realm of the senses; wisdom applied in a practical sense
left: aloofness; innocence
reversed: carelessness; childishness