"No man is an island" is a famous quote from a poem written by John Donne, a 17th-century English poet. The poem is entitled "Meditation XVII." In the context of the poem, Donne uses this phrase to express the idea that every human being is interconnected and depends on others for support and companionship. It suggests that humans are social creatures and cannot exist in isolation. This quote is often used to emphasize the importance of community, empathy, and the interconnectedness of humanity.