You're sitting in your room and meditating when you hear a voice (voice? vibe? thought wave?) saying, "Hi, there! This is G‑d. I've come to reveal Myself to you!"

Is it the real thing? Is it another of your roommate's pranks? Or just your imagination running wild? How to know?

Let me say from the onset that G‑d never revealed Himself to me, at least not quite that way. So I'm not much of an authority on how to tell the real thing. All I can do is look at the numerous Divine revelations reported in the Torah and try to glean some general pointers.

1) It usually doesn't come out of the blue. Abraham first heard from G‑d after 75 years of searching for the truth, finding it, devoting his life to it, and teaching it to the world. Moses first saw G‑d at age 80 — that is, after 80 years of being Moses. And the greatest Divine revelation of all time (that's the one I was at, but I only have a hazy memory of it), at which G‑d revealed Himself on a mountaintop in the presence of the entire people of Israel and the souls of all future generations — that came after 220 years of G‑dly living by the Patriarchs, 210 years of refinement in the "smelting pit" of Egyptian exile, and an intense 49-step process of spiritual advancement by the people during the seven weeks from the Exodus to Sinai.

In the words of Maimonides: "Prophecy comes only to a sage who is great in wisdom and powerful in character, one whose desires never overpower him but who always exercises the power of his mind over his desires, and who possesses an intellect that is broad and true. A person who possesses all these attributes, and who is whole in body, who enters into the orchard of divine wisdom... sanctifies himself, and removes himself from the ways of the masses who follow the frivolities of the times... and whose mind is forever directed Above, focused upon the Divine Throne... and gazing upon the divine wisdom... the divine spirit will come to rest upon him..." (Mishneh Torah, Laws of the Fundamentals of Torah 7:1).

Actually, the Chassidic masters maintain that every Divine revelation does come out of the blue — simply because it utterly transcends whatever "preparations" for it are made by the finite human mind and heart. Still, in order for that "out of the blue" to happen, the recipient of the revelation must first attain his or her utmost potential.

2) You're told to do something. As a rule, when G‑d speaks to people it is to give them a task. And chances are that it'll be a very, very difficult task. G‑d appeared to Abraham to tell him to "go from your land, your birthplace, and your father's house" and found the Jewish people — a task that required him "to be on one side, with the entire world on the other side." Moses' vision at the burning bush was to send him to take the Children of Israel out of Egypt and lead them through the wilderness to the Promised Land (Moses had the sense to turn down the job, and it took G‑d seven days and seven nights of pleading and threatening to get him to accept it). The Prophets were spoken to so that they should take their very unpopular message to the people — a task that entailed the risk, and even the forfeit, of their lives. The revelation at Sinai was to give us the Torah — with its 613 commandments, thousands of by-laws and directives, and millions of pages of (still growing!) commentary.

(A notable exception seems to be the Divine revelation to Abraham recorded at the beginning of the parshah of Vayeira [Genesis 18:1]: the Torah simply relates that "G‑d revealed Himself to him" without stating the purpose of the visit. But our sages are quick to find numerous directives and instructions to be learned from G‑d's visit, from the duty to visit the sick [Abraham was recuperating from his circumcision] to the greatness of hospitality [Abraham interrupted the visit to rush out and offer food and rest to three passing Bedouin].)

In any case, in virtually all the recorded cases of Divine revelation, the person seems to have known that it was G‑d. So I guess that means that if you're not sure it is, then it's probably not.