Leopard does not change its spots.

"Leopards does not change its spots."というフレーズをご存知でしょうか？

以下の引用を読んでみましょう。


Under certain conditions, it seems possible that pigs could fly and leopards change their spots, after all, 'cause the ride-hail industry's leader has suddenly reversed its long-held opposition to tipping.

Uber announced today that it will be rolling out a tipping feature for the service, which has been a cash-free operation since its launch in 2009. As The Verge reported, the in-app tipping option will be available as of today in Seattle, Minneapolis, and Houston, and will be extended to the rest of Uber's American service areas by the end of July.

For years, Uber has maintained a tip-free format for its passenger app, though its early claims that tips were already included in fares didn't last long. Now, a couple years after rival service Lyft built a tipping option into their app, Uber has hopped on the gratuity train as part of its efforts to mend ties with drivers, riders, officials, and anyone else who's paying attention.
(Janet Burns. Eight Years And Umpteen Scandals Later, You Can Finally Tip Your Uber Driver. Forbes. June 20, 2017.)


pigs might flyは以前取り上げましたね。

"Leopards does not change its spots."は直訳すれば、ヒョウの斑模様は変わらない、ということで、変わることのないことの喩えとして使われる表現です。

pigs might flyは、あり得そうもないことを逆説的に表現したものでした。

つまり、どちらの表現もあり得ない事、起こりそうもない事、を言ったものです。

"Leopards does not change its spots."というフレーズは聖書に由来します。

エレミヤ書の13:23に、


Can the Ethiopian change his skin, or the leopard his spots? then may ye also do good, that are accustomed to do evil.
（エチオピヤびとはその皮膚を変えることができようか。ひょうはその斑点を変えることができようか。もしそれができるならば、悪に慣れたあなたがたも、善を行うことができる。）


とあるそうです。

これも逆説の表現であり、罪深い人間は決して善人足り得ず、裁きを受ける運命にあるというのが趣旨となっています。