The Talmud (Chagiga 14b) tells the story of four rabbis who entered the Pardes (literally, the orchard), which is understood to be a metaphor for entering heaven through intense meditation on God’s name.

Ben Azzai gazed [at the Divine Presence – Rashi] and died. Regarding him the verse states, “Precious in the eyes of God is the death of His pious ones” (Psalms 116:15).

Ben Zoma gazed and was harmed [he lost his sanity – Rashi]. Regarding him the verse states, “Did you find honey? Eat only as much as you need, lest you be overfilled and vomit it up” (Proverbs 25:16).

Elisha ben Abuya “cut down the plantings,” which is explained to mean that he became a heretic.

Rabbi Akiva entered in peace and departed in peace.

Pardes is also an acronym for the four levels of interpreting the Torah: P’shat (literal meaning), Remez (allusions in the text), Derush (homilies that can be derived from the text) and Sohd (the mystical level) = PaRDeS.

The story of these rabbis is often considered a warning to those who wish to delve into the mystical depths of Judaism without proper preparation. According to tradition, one should not even consider studying Kaballah (mysticism) until one has learned all of Torah and is at least 40 years of age.

One would never consider studying calculus without a fundamental knowledge of algebra, nor could one understand algebra without mastering basic arithmetic. Similarly, one must be thoroughly versed in Torah knowledge before engaging in the study of Sohd, lest one misunderstand and be led astray.