The Talmudic narrative that later gave the acronym PaRDeS its name, though unrelated to the fourfold interpretive scheme noted elsewhere, is significant enough on its own to warrant telling directly, since it has shaped Jewish attitudes toward mystical speculation for centuries independent of the acronym built on its title word.
The passage (Hagigah 14b) reports that four sages entered the pardes, understood by later tradition as a mystical ascent to contemplate the divine realm rather than a literal garden: Ben Azzai, Ben Zoma, Elisha ben Abuyah (called Acher, "the other," after his apostasy) and Rabbi Akiva. Ben Azzai looked and died. Ben Zoma looked and was harmed, losing his mind or composure. Acher "cut the shoots," read as meaning he became a heretic, on one influential account because he glimpsed a vision leading him to conclude there were "two powers in Heaven" rather than one, a conclusion the tradition regarded as a fundamental rupture of monotheism. Rabbi Akiva alone "entered in peace and departed in peace."
The story became the classic rabbinic warning against unprepared or improperly motivated mystical speculation, cited for centuries by authorities cautioning against premature study of esoteric matters, and it directly informs later Kabbalah's practice of restricting the study of Jewish mysticism to mature, married men of established learning, traditionally forty years old, on the reasoning that Ben Azzai and Ben Zoma's fates show that even great scholars can be destroyed by encountering realities they were not yet fit to handle.