The fat is in the fire

What’s the origin of the phrase ‘The fat is in the fire’?

This proverbial saying is first found in John Heywood’s 1546 glossary A Dialogue conteinyng the nomber in effect of all the Prouerbes in the Englishe tongue:

Nowe if we awarde me this wydowe to wedde,
And that I dryue of tyme, tyll tyme she be dedde:
Than farewell ryches, the fat is in the fyre.
And neuer shall I to lyke riches aspire.

In the above line Heywood was referring to the choice between marriage or wealth and that, if he chose marriage, then ‘farewell riches’.

See also: the List of Proverbs.