Which Lewis Carroll character stated: "The rule is, jam to-morrow and jam yesterday – but never jam to-day"?

"Jam tomorrow" is an expression for a never-fulfilled promise. It originates from Lewis Carroll's 1871 book "Through the Looking Glass and What Alice Found There" This is a pun on a mnemonic for the usage of the Latin word "iam" (or "jam"), which means "at this time", but only when referring to the future or to the past (there is a different Latin word for "now"). In the book, the White Queen offers Alice "jam every other day" as an inducement to work for her:

"I'm sure I'll take you with pleasure!" the Queen said. "Two pence a week, and jam every other day."

Alice couldn't help laughing, as she said, "I don't want you to hire me – and I don't care for jam."

"It's very good jam," said the Queen.

"Well, I don't want any to-day, at any rate."

"You couldn't have it if you did want it," the Queen said. "The rule is, jam to-morrow and jam yesterday – but never jam to-day."

"It must come sometimes to 'jam to-day'," Alice objected.

"No, it can't," said the Queen. "It's jam every other day: to-day isn't any other day, you know."

"I don't understand you," said Alice. "It's dreadfully confusing!"

In modern times, the phrase "jam tomorrow" is often used to describe a variety of unfulfilled political promises on issues such as economic prosperity. With the passage of time "tomorrow" comes around, but there is still no jam because, when "tomorrow" does come, it has become "today"!