"Carpe diem." To almost everyone in the world, that Latin phrase is instantly recognizable and understandable. Popularized greatly by fictional, yet fantastic, English teacher John Keating (played by the unforgettable Robin Williams) in Dead Poets Society, the phrase implores everyone to live every moment.
First introduced in Odes, a book of poems published in 23 B.C., Roman poet Horace encourages readers to "seize the day, put very little trust in tomorrow." He makes the point that we can never know what will happen in the future, so today is all we have. Particularly in the realm of our relationships with friends, family or romantic partners, we should never leave important things unsaid, lest it become too late to express them.