Jam tomorrow

Jam tomorrow or (older spelling) jam to-morrow 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.^[1] 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!"

This is pun, because the Queen is reciting a "rule" that is actually a rule of Latin grammar: "iam" means "now" in Latin, but only when speaking in the past or future. In the present the word for now is "nunc." So, "jam [iam] tomorrow, jam yesterday, but never jam today," is actually a good mnemonic for the rule.

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 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:

"For purposiveness means that we are more concerned with the remote future results of our actions than with their own quality or their immediate effects on our own environment. The “purposive” man is always trying to secure a spurious and delusive immortality for his acts by pushing his interest in them forward into time. He does not love his cat, but his cat’s kittens; nor, in truth, the kittens, but only the kittens’ kittens, and so on forward forever to the end of cat-dom. For him jam is not jam unless it is a case of jam to-morrow and never jam to-day. Thus by pushing his jam always forward into the future, he strives to secure for his act of boiling it an immortality."^[2]

References

Look up jam tomorrow in Wiktionary, the free dictionary.