From Rabbi Aryeh Kaplan, “Meditation and the Bible” (Samuel Weiser or Jason Aronson edition), p. 22; translation of Rabbi Moses Maimonides (Rambam) (1135-1204), Mishneh Torah, Yesodey HaTorah 7:1.
Maimonides on Secluded Meditation
An individual having all the necessary qualifications can delve into the mysteries (Pardes), advancing in these deep, subtle concepts and gaining a firm understanding and perception of them.
At the same time, he must also sanctify himself and separate himself from the ways of the masses, who grope in the darkness of the times. He must achieve constant diligence in not even thinking of non-essentials or considering the current vanities and intrigues.
Such a person must work on himself until his mind is constantly clear and directed on high. He must bind his intellect to the Throne of Glory, striving to comprehend the purity and holiness of the transcendental. He must furthermore contemplate on the wisdom of God in each thing, understanding its true significance, whether it be the highest spiritual entity or the lowliest thing on earth.
The individual who does this immediately becomes worthy of Ruach HaKodesh (the “Divine Spirit”). When he attains this spirit, his soul becomes bound up on the level of the angels ... and he becomes a completely different person. He can now understand things with a knowledge completely different than anything that he ever experienced previously. The level that he has attained is far above that of other men, who can merely use their intellect. This is the meaning of what [the prophet Samuel told] King Saul, "[The spirit of God shall descend upon you, you shall prophesy with them, and you shall be transformed into a different man" (I Samuel 10:6).