SB 11.22.41
svapnam manoratham cettham
praktanam na smaraty asau
tatra purvam ivatmanam
apurvam canupasyati
Translation:
Just as a person experiencing a dream or daydream does not remember his previous dreams or daydreams, a person situated in his present body, although having existed prior to it, thinks that he has only recently come into being.
Purport:
The objection may be raised that sometimes when experiencing a dream one actually remembers a previous dream. Srila Visvanatha Cakravarti Thakura replies that by the mystic power of jati-smara one can remember one’s previous body, and as is well known, “The exception establishes the rule.” Normally, conditioned souls do not perceive their past existence; they think, “I am six years old” or “I am thirty years old,” and “previous to this birth I did not exist.” In such material ignorance one cannot understand the actual situation of the soul.