A Hypothetical Dialogue
Interrogator: In the first line of your sonnet which reads, "Shall I compare thee to a summer's day", would not "a spring day" do as well or better?
Witness: It wouldn't scan.
Interrogator: How about "a winter's day"? That would scan all right.
Witness: Yes, but nobody wants to be compared to a winter's day.
Interrogator: Would you say Mr. Pickwick reminded you of Christmas?
Witness: In a way.
Interrogator: Yet Christmas is a winter's day, and I do not think Mr. Pickwick would mind the comparison.
Witness: I don't think you're serious. By a winter's day one means a typical winter's day, rather than a special one like Christmas.
--Alan M. Turing, "Computing Machinery and Intelligence"
[Mind, Vol. LIX, No. 236 (1950)]