David Michael Letterman:
(Indianapolis (Indiana), 12 April 1947) is an American television presenter, comedian and television producer. He is also co-owner of a team in the IndyCar Series.
He became known in America in the 1980s through his long-running show Late Night with David Letterman on NBC. He then worked at CBS in the 1990s, presenting the Late show with David Letterman. His humour is described as ironic and absurd, and he is heavily influenced by another American comedian, Johnny Carson, who hosted The Tonight Show for years.

Autumn, the annual dismissal of summer.

“Autumn, the annual dismissal of summer.” is a concise, metaphorical definition of autumn.
– “Dismissal”:
means sending someone or something away, or bringing it to an end.
– Summer is personified as though it were an employee formally dismissed each year.
– The phrase therefore means:
‘autumn is the season that annually ends and replaces summer’.
Its charm comes from the slightly cold, bureaucratic word ‘dismissal’ applied to a natural seasonal change.
✍️ Origin and attribution:
The sentence is ‘frequently attributed online to David Letterman’, but there appears to be ‘no reliable primary source’—such as a dated broadcast transcript, interview, or published work—confirming that he wrote or said it. It is therefore safest to label it:
> “Attributed to David Letterman”
Letterman is also credited with a different, better-known autumn joke:
> “Fall is my favorite season in Los Angeles, watching the birds change color and fall from the trees.”
That quotation may have contributed to autumn-related sayings becoming attached to his name.
Bottom line:
– Meaning: autumn annually brings summer to an end.
– Style: personification and dry humor.
– Author: ‘unverified’; commonly—but not securely—attributed to David Letterman.
– Exact origin: not firmly documented.