Meaning of the word "the mill cannot grind with water that is past" in English

What does "the mill cannot grind with water that is past" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

the mill cannot grind with water that is past

US /ðə mɪl ˈkæn.ɑːt ɡraɪnd wɪð ˈwɔː.tər ðæt ɪz pæst/
UK /ðə mɪl ˈkæn.ɒt ɡraɪnd wɪð ˈwɔː.tər ðæt ɪz pɑːst/
"the mill cannot grind with water that is past" picture

Idiom

you cannot change or use things that have already happened or passed; do not waste time worrying about the past

Example:
I know you regret your decision, but the mill cannot grind with water that is past.
Stop crying over your old mistakes; the mill cannot grind with water that is past.