Terry Pratchett said this quote

“ We all think we understand each other,' Kin heard Silver say. 'We eat together, we trade, many of us pride ourselves on having alien friends - but all this is only possible, only possible, Kin, because we do not fully comprehend the other. You've studied Earth history. Do you think you could understand the workings of of the mind of a Japanese warrior a thousand years ago? But he is as a twin to you compared with Marco, or with myself. When we use the word cosmopolitan we use it too lightly - it's flippant, it means we're galactic tourists who communicate in superficialities. We don't comprehend. Different worlds, Kin. Different anvils of gravity and radiation and evolution. ”