You can't teach an old dog new tricks

Cultural  

1. People who have long been used to doing things in a particular way will not abandon their habits. (Compare It's never too late to mend.)

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Example Sentences

The cliché "You can't teach an old dog new tricks" is simply not true.

From Golf Digest • Sep. 22, 2016

You can't teach an old dog new tricks, pardner.

From Tom Swift and His Giant Cannon, or, the Longest Shots on Record by Appleton, Victor [pseud.]

A mildewed maxim runs: "You can't teach an old dog new tricks."

From Further Adventures of Lad by Terhune, Albert Payson

We will assume that you are not so young as you wish you were, and that you have committed to memory the fatalistic, hoary lie, "You can't teach an old dog new tricks."

From Certain Success by Hawkins, Norval A.