/dev/zero

I was flipping through the mail I had just brought in from the mailbox, standing by the front hall table.
“That must be yesterday’s mail.” Mom says.
“No, it’s today’s mail.”
“There’s no mail delivery today.” she says.
“Why wouldn’t there be mail delivery today?” I ask.
“It’s a holiday.”

“No, tomorrow is the holiday.”
“Tomorrow is Saturday.” she answers. “So the holiday is observed today.” (She’s apparently forgotten that the post office delivers on Saturdays.)
“No, it’s today’s mail.”
“It can’t be. It’s yesterday’s mail. We’re a day behind bringing the mail in from the mailbox.”
“It can’t be yeseterday’s mail. Dad brought the mail in from the mailbox last night when he got home.” I remind her.
“But that was from the day before.”
Not believing Mom could make such an error in reasoning I point out “Mom, he brougth the mail in last night. Therefor once he brought the mail in, regardless of when it was delivered, the mailbox was empty. Therefor any mail that was in it when I went out to check it had to have been delivered today.”
“…. Do you have to apply logic to this argument?”