1. They always find fault with me.
2. The always try to find fault with me .
In sentence 1, the verb find has they for its subject : hence the verb find is limited by person and number. We , therefore call it a INFINITE VERB.
(It will be noticed that all verbs in the Indicative, Subjunctive and Imperative Moods are Finite , because they are
limited by the person and number of their subject) .
In sentence 2 , to find merely names the action denoted by the verb find and is used without mentioning any subject. It is , therefore , not limited by person and number , as a verb that has a subject and is , therefore called the VERB INFINITE OR SIMPLY THE INFINITIVE.