"All things are difficult, before they are easy."

Modals

Modals in the past:

https://www.helpforenglish.cz/article/2006062302-minula-modalni-slovesa

https://learningenglish.voanews.com/a/everyday-grammar-could-have-should-have-would-have/3391128.html

https://www.youtube.com/watch?v=1PY6xIDkIj4