Based on the Gregorian calendar, the days of each month have been assigned to one of the Oracle Cards using a formula postulated by Olney Richmond in his book 'The Mystic Test Book'.

The mathematical formulas provided by Richmond placed the cards in the orientation shown in the table below.  However, notice the symmetry caused by the placement of the cards in relation to the start of each month.  Each successive month starts with the previous months start card minus two positions.  At August 1st, it loops over to the Diamonds, skipping the King which maintains the basic symmetry.  Among other things, this shows that even though there is a mathematical language that operates under the surface of this science, the symmetric nature of the outer appearance may be of more use to the awakening of the artistic--or abstract--mind.

Notice that the Joker occupies the position between and
The little Joker occupies the date for February 29th.