thin edge of the wedge

Idioms  

1. A minor change that begins a major development, especially an undesirable one. For example, First they asked me to postpone my vacation for a week, and then for a month; it's the thin edge of the wedge and pretty soon it'll be a year. This term alludes to the narrow wedge inserted into a log for splitting wood. [Mid-1800s]

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Example Sentences

Rewriting, oh pardon me, repurposing Roald Dahl's books is just the thin edge of the wedge.

From Salon • May 30, 2023

Lithwick: So this is the thin edge of the wedge.

From Slate • Apr. 19, 2017

But, sometimes, it is hard to identify the thin edge of the wedge that eventually cracks open the door to greater freedom.

From Washington Post • Mar. 22, 2016

Only a little; but it may be the thin edge of the wedge, the crack in the wall that will open, later, onto what?

From "Cat's Eye" by Margaret Atwood

The first thin edge of the wedge has been inserted: the sword trembles to its fall: c'est le commencement de la fin.

From Mrs. Geoffrey by Duchess