Jam tomorrow

Jam tomorrow or jam to-morrow (older spelling) is an expression for a never-fulfilled promise. Some pleasant event in the future, which is never likely to materialize. 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" (formerly often written and pronounced "jam"), which means "at this time", but only in the future or past tense, not in the present (which is instead "nunc" "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!"
The passage inspired the title of the 1979 musical "But Never Jam Today".
Usage.
In more recent times, the phrase has been used to describe a variety of unfulfilled political promises on issues such as tax, and was used by C. S. Lewis in satirizing the extrapolation of evolution from biological theory to philosophical guiding principle, in his 1957 poem "Evolutionary Hymn":
John Maynard Keynes also makes use of the image of "never jam today" in order to portray vividly the tendency to excessive saving which may lead to economic stagnation:
British folk musician Billy Bragg uses it in his 1986 song "The Home Front":