Sefer Yetzirah
Solomon Judah Löb Rapoport notes that according to the Masoretes there are ten vowel sounds. He suggests that the passage in the "Sefer Yetzirah", which discusses the manipulation of letters in the creation of the world, can be better understood if the Sephirot refer to vowel sounds. He posits that the word "sephirah" in this case is related to the Hebrew word ("to retell"). His position is based on his belief that most Kabbalistic works written after "Sefer Yetzirah" (including the "Zohar") are forgeries.