What role does the infinitive phrase play in this sentence To be persistent is a sign of stubbornness?

In the sentence "To be persistent is a sign of stubbornness," the infinitive phrase "to be persistent" acts as the subject of the sentence.

Here's how to break it down:

* Infinitive phrase: "to be persistent"

* Infinitive: "to be"

* Subject: The entire infinitive phrase "to be persistent" is the subject of the sentence.

* Verb: "is"

* Predicate: "a sign of stubbornness"

The sentence essentially means: "Being persistent is a sign of stubbornness." The infinitive phrase is acting as the noun that is being described by the rest of the sentence.