Sepher Yetzirah 4.1 Seven doubles: beth, gimel, daleth, kaph, pe, resh, tau.
They direct themselves with two tongues:
- Beth - bheth
- Gimel - ghimel
- Daleth - dhaleth
- Kaph - khaph
- Pe - phe
- Resh - rhesh
- Tau - thau.
A structure of soft and hard, strong and weak.
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