The mothers are the letters Alef, Mem, and Shin—the first, middle, and penultimate letters of the Alphabet. They are the energy for the four seasons of the year.

Shin is summer; Mem is winter; Alef is fall and spring.

(Shin is fire (the Hebrew for fire is “eish”), and hence provides the heat of summer; Mem is water (as in the Hebrew “mayim”) and hence provides the coldness of winter; Alef is the great harmonizer, creating the balance between heat and cold. Alef is air (as in the Hebrew word “ahvir”).

The seven doubles are the letters that have two sounds, plosive and fricative: Bet, Gimmel, Dalet, Kaf, Pei, Reish, and Tav. So, for example, the Bet has a double, namely the Vet. B is the plosive, the harsher sound, and its softer double is the V, the fricative.

Only four of these letters—Bet, Kaf, Pei and Tav (in the case of Ashkenazic Jews) are still pronounced as doubles. Bet, as we said; Kaf and Khaf (as in the German Bach); Pei and Fei; Tav and Sav. The double sounds of the Gimmel and the Dalet is maintained only among the Yemenite Jews. The double sound of the Reish has been entirely lost.

The seven doubles correspond to the seven days of the week, the seven years of the sabbatical and the seven sabbaticals in a Jubilee.

The other twelve letters are referred to as the twelve elementals and correspond to the twelve months of the year, the twelve tribes and the twelve constellations of the Zodiac.

The three mothers and seven doubles also refer to the Ten Sefirot. The three mothers refer to the three intellectual faculties, Chochmah, Binah, Da’at—which “give birth” to the seven emotions, which are called “doubles.”