Jam tomorrow

Jam tomorrow or jam to-morrow (older spelling) 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 iam in Latin (note i/j conflation in Latin spelling), which means “now”, but only in the future or past tense, not in the present (which is instead nunc). 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 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 satirising the extrapolation of evolution from biological theory to philosophical guiding principle, in his 1957 Hymn to Evolution, a poem based on Lead us, heavenly Father, lead us and set to the same tune, Mannheim:

Lead us, Evolution, lead us

Up the future's endless stair:
Chop us, change us, prod us, weed us.
For stagnation is despair:
Groping, guessing, yet progressing,
Lead us nobody knows where.

Wrong or justice in the present,
Joy or sorrow, what are they
While there's always jam to-morrow,
While we tread the onward way?
Never knowing where we're going,
We can never go astray.

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:

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