Is the phrase boldly go where no man has gone proper English?

The phrase "boldly go where no man has gone before" is actually a slightly modified version of the original line from the TV series Star Trek: "to boldly go where no man has gone before".

Here's why the original is considered more grammatically correct:

* "To boldly go" is an infinitive phrase used as the subject of the sentence. This is grammatically sound.

* "Boldly go where no man has gone before" is a complete sentence, making it a bit redundant and slightly awkward.

However, both versions are commonly used and understood. The original is more grammatically accurate, but the modified version is widely accepted and familiar due to its use in popular culture.