Rabbi Abba said (Sefer ZOHAR 1:99b):
One day I came to a city of the East (e.g. India), and they told me some wisdom that they had inherited from ancient times. They also had books explaining the wisdom, and they brought me one such book. In this book it was written that when a person meditates in this world, a spirit (Ruach) is transmitted to him from on high. The type of spirit depends on the desire to which he attaches himself. If his mind attaches itself to something lofty and holy, then that is what he transmits down to himself. But if his mind attaches itself to the Other Side (Sitra Achra), and he meditates on this, then that will be what he transmits down to himself.
They said, “It all depends on word, deed, and the individual’s desire to attach himself. Through these, he transmits downward to himself that side to which he becomes attached”. In that book I found the (idolatrous) rites and practices involved in the worship of the stars and constellations. It included the things needed for such rites, as well as instructions how one must meditate in order to transmit their (influence) to himself. In the same manner, one who wishes to attach himself on high through Ruach HaKodesh (Holy Spirit) must do so with deed, word, and the desire of the heart, meditating in that area. This is what it depends on when one wishes to bind himself to something and transmit its influence to himself … I said to them, “My children, the things in that book are very close to the teachings of the Torah. But you must keep yourselves from these books in order that your hearts not be drawn away from serving G – d.” All these books can confuse a person. This is because the people of the East were great sages, who inherited this wisdom from Avraham. He had given it to the sons of his concubines, as it is written, „To the sons of the concubines that Avraham had taken, Avraham gave gifts (see Genesis / Bereshit 25:6). This was originally true wisdom but later it was drawn into many idolatrous sides.
Taken from MEDITATION AND KABBALAH by Rabbi Aryeh Kaplan