The allegory goes something like this: if a frog is tossed suddenly into a boiling pot of water, it will instinctively jump out.

However, if the water is tepid when the frog is placed into the pot, and the heat is then brought up to boil the water slowly, the frog won't recognize any danger and will gradually be cooked to death. The fable implies the often unintentional, other times blatant, unwillingness of people to react to eminent, often dangerous threats that boil up slowly as opposed to suddenly. Sometimes they will even normalize and excuse it.

The best stews are allowed to simmer for a long time at a low heat. That lets all of the ingredients meld together, creating complex, textured, and diverse flavors. But when the stew is left in the hands of a diabolical chef, adding unwanted ingredients can make the meal deadly.