R. Kaplan in his
commentaries on Sefer Yetzirah
describes an interesting unfication meditation involving
the letters
Shin and
Mem. They represent the two outer
pillars of
Gevurah, Severity, and
Chesed, Mercy. As described in R. Kaplan's commentaries, one says
these two letters with the vowels o, a, e, i, and u, keeping first the o on
Shin, and cycling thru the 5 vowels on the Mem. Then, we change to "a", and
cycle again. This is done by breathing once per vowel. Also, this should
be done by first contemplating some unification which we desire to have
before starting, and by impressing on ourselves the firey image of Shin and
the watery image of Mem.