The Moments of Happiness is the first number in act 2 of Cats.
This number begins slowly, as the cast gradually make their way onstage, often through the auditorium, playing with the audience as they go. Old Deuteronomy often spends the interval sitting alone onstage, reflecting on the tribe's energy and hostility towards Grizabella. Eventually he begins to sing, trying to explain the philosophy behind the tribe's customs. the song is quiet and reflective. The mystical twins, Coricopat and Tantomile, channel Old Deuteronomy's energy into Jemima, who explains the concept in far simpler language, singing "Moonlight, turn your face to the Moonlight".
The text is from T S Eliot's "The Dry Salvages" in Four Quartets
The moments of happiness . . .
We had the experience but missed the meaning
And approach to the meaning restores the experience
In a different form, beyond any meaning
We can assign to happiness . . .
The past experience revived in the meaning
Is not the experience of one life only
But of many generations - not forgetting
Something that is probably quite ineffable
Moonlight, turn your face to the moonlight
Let your memory lead you
Open up, enter in
If you find there the meaning of what happiness is
Then a new life will begin