During the XIII° century begun the cabal. On the one hand, Moïse of Leon wrote a monumental work, Zohar, which aimed only one elite but became very popular. On the other hand, Abraham Aboulafia undertook to spread to general public his technique of prayer, but its writings had a completely confidential posterity.
Abraham Aboulafia obliged his spirit, while praying, to do permutations of Hebraic letters according to definite progressions.
Why doing a systematic work of letters permutations on syllables or words could be advantageous to a spiritual progression?
Because the mental, totally occupied by this task, breaks by doing this, with its inclination about mental association. This technique has the advantages of not requiring the intelligence, which would use the associative process, and in the same time to be enough complicated to monopolize all the ATTENTION.

It consists in being armed with the monologic prayer
"Lord Jesus Christ, Son of God,
have mercy on me, a sinner",
which one has to be recited continuously, and according to the rhythm of breathing.

It increases the monotropism of the thought by bringing back unceasingly to the memory of God.
It is also propitious to interior perception, proportionate with the work of the attention, and auspicious to desapropriation, if operative humility is added to it.