is forgetting the same as never knowing?
(the mishna discusses the consequences of breaking shabbat when one has forgotten that it is shabbat, or what shabbat is. leads to a discussion of what does it mean to forget. Rav and Shmuel argue that it is the same as a kidnapped child who has never been taught about Shabbat. Reish Lakish and R. Yochnan argue that forgetting implies prior knowledge, that the kidnapped child never had. for english translation of this talmud page, see here)