“Yours affectionately,

“Pia.”

To which Trix replied:

“My dear Pia,

“My rainbow shines after every shower, and is brightest against the darkest clouds. When I look towards the darkest clouds I wait for the rainbow.

“Yours,

“Trix.”

And Pia wrote:

“My dear Trix,

“What happens when there is no longer any sun to form a rainbow?