The moment Paul McCartney played ‘Let It Be’ to the rest of The Beatles, 1969

I love to hear the embryo of a classic song. Here in this case he had the chords and timing down right off the bat. It didn't need "improving" or shape. To their credit the others knew not to touch it as it sounded whole and complete. They could have said things like, "what if you went to a major chord there" or "slow it down" or "shorten it", etc.