"One does not simply walk into Mordor."

Writing tip: It's common in English to use "you" to mean "people in general" rather than a specific person.

When using this generic "you," one can replace it with "one" instead.

(See what I did there.)

It's a tiny switch that makes the sentence more formal, elegant, presumptuous, like ancient wisdom.

Probably mostly relevant to people writing speeches or fantasy.