Lesson 9 | Infinitives

[1] About Infinitives

An infinitive is a verbal noun. Or, in other words, an infinitive is a verb functioning as a noun. This means that it has some verbal characteristics and some noun characteristics. Like verbs, infinitives have tense-form (present, aorist, etc.) and voice. Like nouns, infinitives can take the article, function as the object of a preposition, and even serve as the main verb’s subject or direct object.
Infinitives are like participles in a couple of key ways. First, they are non-finite verbs and so do not have a built-in subject. Second, their tense-form communicates aspect and not time. Like participles, infinitives take their time from the context.
The Four Rules
There are four important rules regarding the function of infinitives:
Non-articular = adverb, articular = noun
Without the article, infinitives are adverbial (they describe or complement the main verb). With the article (i.e. “articular”), infinitives act like nouns.
Neuter article
When infinitives take the article, the article is always neuter.
Accusative subject
When an infinitive takes a distinct subject, that subject will be in the accusative case.
Preposition + article + infinitive = ?
When articular infinitives are a part of a prepositional phrase, they often have a particular meaning (we will learn more about this later in the lesson).

Seeing The Rules in Action

Εμοὶ γὰρ τὸ ζῆν Χριστὸς καὶ τὸ ἀποθανεῖν κέρδος.

For to me to go on living is Christ, and to die is gain.

—Philippians 1:21
First, note that both infinitives have a nominative, neuter, singular article. When infinitives take the article, the article is always neuter. Second, you can see that both infinitives are acting like nouns. Each infinitive is the subject of its respective clause. Both clauses are verbless with an implied “is.”
Third, notice that both infinitives also communicate aspect even as they function like nouns. τὸ ζῆν is a present, active, infinitive from ζάω. So, it communicates imperfective aspect. Paul portrays his living from within as the action happens: “to be living” or “to go on living.” τὸ ἀποθανεῖν is an aorist, active, infinitive from ἀποθνῄσκω. So, it communicates perfective aspect. Paul summarizes the whole action from the outside: “to die.” 

Χριστὸς Ἰησοῦς ἦλθεν εἰς τὸν κόσμον ἁμαρτωλοὺς σῶσαι

Christ Jesus came into the world to save sinners

—1 Timothy 1:15
First, notice that, like a verb, σῶσαι takes a direct object: ἁμαρτωλοὺς.
Second, look at how the infinitive functions adverbially to tell us more about the main verb. In this sentence, σῶσαι explains the purpose of ἦλθεν. Why did Jesus come? He came in order to save sinners. 
Third, pay attention to what the tense-form communicates. As an infinitive, σῶσαι communicates aspect and not time. The infinitive draws its time from the main verb. 
Summary
I hope you do not feel overwhelmed at this point. You do not need to master all this information right now. It will become more familiar to you as you work through this lesson. For now, remember three things:
Infinitives are verbal nouns.
Like verbs, infinitives communicate aspect and voice, and can take subjects, objects, and modifiers.
Like nouns, infinitives can function as the subject or object of a main verb. They can also take a neuter article.