There can be no denying the perils of the esoteric and the occult.
The common people were simply advised to keep away from subjects they did not know enough about, a little knowledge being a dangerous thing in any field.
And as far as Torah is concerned, since it is a live wire connecting us with God, anyone who gets involved without taking precautionary measures runs the risk of being electrocuted.
It was in this sense that Kabbalah used to be considered a field that was not accessible to all.
There was a need for special knowledge and sensitivity to be able to enter into the realm of the hidden.
When studying the Talmud, it is all too apparent when one does not quite comprehend a passage, because the Talmud speaks about people, animals, the mundane affairs of men.
A student can easily discern what he grasps and what he does not.
But when studying the Kabbalah—which speaks about sefirot, angels, Divine lights, and vessels—the ability to distinguish one's own lack of understanding is far more difficult, so that the subtle danger of misconception is a sad inevitability accompanying such study.
All of this is not intended to divert attention from the fact that the Torah, including the manifest and the hidden, is all one.
To be sure, it is said that it has seventy faces.
Indeed, some sources say it has six hundred thousand faces, because that is the number of souls who received the Torah when it was revealed.
And each one has, to this day, his own understanding of it, his own orientation and point of view.
–Rabbi Adin Steinsaltz
From On Being Free by Rabbi Adin Steinsaltz