"TO LOVE ANOTHER PERSON IS TO SEE THE FACE OF GOD"- LES MISERABLES---
"THERE'S A SPECIAL KIND OF PEOPLE KNOWN AS SHOW PEOPLE... WE'RE BORN EVERY NIGHT AT HALF HOUR CALL!"--- CURTAINS
SOUTH PACIFIC, accepting people who don't look like you do into your own life INTO THE WOODS, accepting the imperfections and painful realities of life and one's responsibilities to oneself and one's community FUN HOME, accepting that you, under other historical conditions, might be just as ****ed up as your parents FALSETTOS, accepting that "everyone hates their parents." FOLLIES, accepting just being dressy when you are no longer juicy or, if you can't afford to be dressy at that age, accepting being neither dressy nor juicy
If "acceptance" means tolerance of diversity, then ALL the R&H musicals (and their imitators) are basically built on that theme. Best12 is right that Hammerstein starts the trend with SHOW BOAT.