Sefer Yetzirah 1:10

The letters on three levels of unity.

PLEASE NOTE: I must apologize for an error I made in the class listing the Sheva kefulot (the seven doubles). These are not the letters מנצפ"ך (mem, nun, tzadi, peh, chaf) as I said, but rather the letters bet, gimel, dalet, kaf, peh, raish, tav. These letters each have two forms -- with a dagesh or without one. See our previous video Sefer Yetzirah 1:2

My apologies again