Responsa על ברכות 111:3

Regarding the Talmudic tale of Bar Haddaya (Berachot 56a:2), who when given a fee would interpret dreams positively, and when not paid, would interpret them as negative omens. It is also said there (ibid.) that Rava found a book that fell from his hands, and in it was written 'All dreams follow the mouth'. We are astounded by this and ask [in a dream] whether it is possible that heavenly decrees are affected by human interpretation. Is this meant to be understood literally, that dreams depend on their interpretation, for better or for worse? Or is it not to be understood this simple way, since heavenly decrees do not change? For Bar Haddaya himself was nothing but a dream interpreter, and why was it then written in his book that 'all dreams follow the mouth'?

They responded: Do you not know, and have you not heard, that there are some people whose birth-sign accords them poor eyes or tongues? Others are given weak legs. Many sicknesses originate from bad eyes, and many die from it, as it says (cf. Talmud Yerushalmi Shabbat 14:3) "Ninety nine die from the evil eye, and one in the way of the earth." So too, sometimes Satan is given permission to wreak destruction, as in the case of Miriam the Hairbraider¹Who was the mother of a sorcerer, according to the Talmud in Shabbat 104b:5. She is misidentified as the mother of Jesus in uncensored versions of Tosafot on Chagigah 4b:11. Others have well-functioning legs, as it says (Genesis 30:30) "God has blessed you at my feet." Do not wonder, for there are those whose birth-sign allows them to interpret dreams and their interpretation is true, for better or for worse, as long as they fit the issue at hand. Bar Haddaya was such a person, and the interpretations that came true were not because of him but because of his sign. It was for this reason that Rava was angry and cursed him (Berachot 56a:16). As to what he found written in the book, that 'all dreams follow the mouth', only applies to those born under such a sign. All this they responded to me after the third time I asked. After some time they said: Do not ponder too much on our words, for we have informed you the truth and mystery is deep.