וַיֹּאמֶר אָכֵן יֵשׁ יְהוָה בַּמָּקוֹם הַזֶּה וְאָנֹכִי לֹא יָדָעְתִּי. (בראשית כח:טז)
And Jacob said “Surely Hashem is in this place, and I didn’t know!” (Bereishis 28:16)
Yaakov dreams of Angels ascending and descending between the Kisa Hakavod and this world. He wakes up astounded—is this a dream or is this real? He comes to the conclusion that: “Behold, there is Hashem in this place” and then he adds “And I didn’t know!” The question is obvious: If he didn’t have an inkling in advance, obviously he would be surprised to find Hashem in this place. What does “I didn’t know!” add?
A person can dream about all kinds of things, and when he wakes up in the morning, he realizes ‘it’s only a dream’ and that it isn’t real. So how is a prophet to know if what he dreamed was a prophecy with meaning, a real dream with meaning or a simple dream without any meaning at all. The Chanukas Hatorah answers this question via a parable: The Gemora tells us in Brachos 55B that a person only dreams about things that he thought about during the day. “Rava said I don’t think anyone ever dreamed the dream of seeing an elephant going through the eye of a needle. The reason for this is obvious, because it never crossed anyone’s mind. Hence we see that a person only dreams at night about things (and mutations thereof) that he thought about during the day. Yaakov Avinu exclaims as follows: I never thought that there was Hashem here, so it could not have been a dream. Thus it must be a prophecy (by Yaakov there was no third option of a meaningless dream), and he built an altar there.
Many times I am asked the question after someone had a troubling dream “Should I be concerned, and ameliorate the dream? Or should I just write it off?” I have learnt from my rabbeim that the vehicle for using dreams to reveal ideas is sent from Hashem to those people who control their thoughts during the day. But someone whose mind wanders aimlessly—conjuring up various ideas and images during the day—when he dreams, his dreams are only dreams.
In summation, regular people could toss and turn in bed, fretting away about self-inflicted paranoia, because their thoughts are not controlled. If, however, one finds himself dreaming of doing good deeds and mitzvohs, one should take comfort in this because he was thinking consciously or subconsciously, about Torah and Mitzvos. Serious thinkers are serious dreamers.