I like in particular Aryeh Kaplan's wonderful translation, since he gives both the Hebrew and the English text. Cover of A. Kaplan's Sefer Yetzirah . It discusses the various combinations of two letters and their possible meanings. It also touches a bit on a system of meditation later developed more fully by Abulafia. The Zohar states that a kiss is the merging of one breath with another.
Love begins with the physical attraction.
Then, as lovers begin communication, they begin to speak. A they get closer, they stop speaking and are merely aware of each other's breath. Finally, they come closer still, and their communication becomes a kiss, at which point they are actually in physical contact. At this moment, in the kiss, they are aware of each other''s life force. Kissing is thus a natural consequence of increased intimacy in speech.