物极必反的英文：
[Literal Meaning]
things/extreme/must/turn opposite
Things will be develop in the opposite direction when they become extreme.

[解释]
事物发展到极点，会向相反方向转化。

[Explanation]
No extreme will hold long.

[例子]
你要相信物极必反的道理，这样逼他最终会让他走上绝路的。

[Example]
You should believe that no extreme will hold long. Forced like this, he will head for his doom sooner or later.

[英文等价词]
Too much water drowned the miller.

"when a thing reaches its limit, it turns round;a thing turns into its opposite if pushed too far "
物极必反