An infinitive phrase is a group of words that contains an infinitive (to + base form of a verb) and any other object or modifier.
Infinitive phrases can work as <u>nouns</u>, <u>adjectives</u>, or <u>adverbs </u>in a sentence. When used as nouns, they can subsitute the subject or the object of the sentence and, therefore, perform or receive the action of the main verb.
In this example, the main verb (is) refers to the subject of the sentence, which is being substituted by the infinitive phrase (To speak clearly).
I've always thought that the book should be renamed - George and Lennie - Of Jobs and Men Or - The Life of George and Lennie Very simple titles, haha :P
