The quote "Once you hear something, you can never return to the time before you heard it" from Jonathan Safran Foer’s "Everything Is Illuminated" speaks to the irreversible impact of knowledge and experiences on our lives. It highlights how the act of learning alters our perceptions and memories, creating a permanent shift in our understanding of the world.

This idea emphasizes that certain revelations, once encountered, cannot be forgotten or unlearned, influencing our choices and interactions henceforth. It suggests that awareness carries both enlightenment and burden, shaping our future despite the desire to return to innocence.