Infinitivesverbal nouns; complementary & articular
An infinitive is a verbal noun — "to loose," "to be." This lesson covers what an infinitive is, the present, aorist, and perfect infinitives (active and middle/passive), complementary infinitives after verbs like δύναμαι, θέλω, μέλλω, and the articular infinitive (διὰ τό, εἰς τό, ἐν τῷ, μετὰ τό, πρὸ τοῦ + infinitive) with its accusative subject and purpose/result uses. Infinitive aspect is not time, and the aorist infinitive takes no augment.
- Explain what an infinitive is — a verbal noun with aspect and voice but no person/number/mood
- Recognize present (λύειν), aorist (λῦσαι, λυθῆναι), and perfect infinitives, and εἶναι
- State that infinitive aspect is not time and the aorist infinitive takes no augment
- Recognize complementary infinitives after δύναμαι, θέλω, μέλλω, ἄρχομαι
- Read the articular infinitive (διὰ τό / εἰς τό / ἐν τῷ / μετὰ τό / πρὸ τοῦ + inf) as cause, purpose, or time
- Recognize the accusative subject of an infinitive and that μή negates an infinitive
- Parse infinitive forms and translate complementary and articular constructions
- Infinitive = “to [verb]” — a verbal noun.
- Present λύειν, aorist λῦσαι; εἶναι = “to be.”
- ἐν τῷ + inf = “while”; διὰ τό + inf = “because.”
- Do only the first 2–3 trainer sets today.
CorePart 1: What an Infinitive Is
An infinitive is a verbal noun — "to loose," "to believe." It names an action without specifying a subject or asserting it. It has tense (aspect) and voice, but no person or number, and no mood.
Because it is partly a noun, an infinitive can be the subject or object of a verb, complete the meaning of another verb, or — with the article — function as a full noun phrase. Because it is partly a verb, it has aspect (present, aorist, perfect) and voice (active, middle/passive), and it can take objects.
Infinitive aspect, like the other non-indicative forms, is not time: a present infinitive views the action as ongoing, an aorist as a whole, a perfect as completed-with-results. The aorist infinitive takes no augment.
ReferencePart 2: Infinitive Forms — λύω
Surface forms. The two you will meet most are the present active (-ειν) and the aorist active (-σαι).
| Tense | Active | Middle/Passive |
|---|---|---|
| Present | λύειν | λύεσθαι |
| Aorist | λῦσαι | λύσασθαι (mid) / λυθῆναι (pass) |
| Perfect | λελυκέναι | λελύσθαι |
CorePart 3: Complementary Infinitives
The simplest use: an infinitive completes the meaning of a "helping" verb.
After verbs like δύναμαι ("be able"), θέλω ("wish"), μέλλω ("be about to"), ἄρχομαι ("begin"), and ὀφείλω ("ought"), an infinitive completes the thought: δύναται σῶσαι — "he is able to save"; θέλω βαπτισθῆναι — "I want to be baptized"; μέλλει ἔρχεσθαι — "he is about to come."
CorePart 4: The Articular Infinitive
Greek can put the neuter article in front of an infinitive, turning it into a noun phrase. With a preposition, this becomes a compact clause — extremely common in Luke-Acts and Paul. You met these in passing in Lesson 9.
| Construction | Sense | English |
|---|---|---|
| διὰ τό + inf | cause | because… |
| εἰς τό + inf | purpose/result | in order to / so as to… |
| πρὸς τό + inf | purpose | in order to… |
| ἐν τῷ + inf | time (contemporaneous) | while / when / as… |
| μετὰ τό + inf | time (subsequent) | after… |
| πρὸ τοῦ + inf | time (prior) | before… |
| τοῦ + inf | purpose | in order to… |
PracticeWorked Examples — Infinitives in the NT
Eighteen infinitive forms from NT vocabulary — present, aorist, perfect; active and middle/passive — including complementary and 2nd-aorist/μι-verb infinitives. Surface form first; memorize the irregular and μι-verb infinitives. Attestation checked against the Greek NT.
PracticeTranslation Exercises
Translate, identifying the infinitive’s job (complementary or articular).
- οὐ δύναται ὁ υἱὸς ποιεῖν οὐδέν.
- ἦλθεν ὁ υἱὸς τοῦ ἀνθρώπου διακονῆσαι καὶ δοῦναι τὴν ψυχὴν αὐτοῦ.
- ἐν τῷ σπείρειν αὐτὸν, ἃ μὲν ἔπεσεν παρὰ τὴν ὁδόν.
- διὰ τὸ μὴ ἔχειν ῥίζαν ἐξηράνθη.
- θέλω βαπτισθῆναι ὑπὸ σοῦ.
- καλόν ἐστιν εἰσελθεῖν εἰς τὴν ζωήν.
2. The Son of Man came to serve and to give his life. (purpose infinitives; cf. Mark 10:45.)
3. While he was sowing, some [seed] fell along the path. (ἐν τῷ + inf = "while"; cf. Mark 4:4.)
4. Because it had no root, it withered. (διὰ τό + inf = cause; cf. Mark 4:6.)
5. I want to be baptized by you. (complementary inf; cf. Matt 3:14.)
6. It is good to enter into life. (inf as subject; cf. Mark 9:43.)
ReferenceVocabulary Notes
Infinitive markers and verbs that take complementary infinitives.
| εἶναι | (inf of εἰμί) | to be |
| δύναμαι | δύναμαι + inf | I am able (to) |
| θέλω | θέλω + inf | I wish, want (to) |
| μέλλω | μέλλω + inf | I am about (to) |
| ἄρχομαι | ἄρχομαι + inf | I begin (to) |
| διὰ τό + inf | — | because (cause) |
| ἐν τῷ + inf | — | while, when (time) |
| εἰς τό + inf | — | in order to (purpose) |
Deep DiveOptional Deep Dive — A Cultural Note — The Infinitive as Greek’s Compression Tool
The articular infinitive lets Greek pack a whole clause into a few words. Where English needs "because they did not have a root," Greek writes διὰ τὸ μὴ ἔχειν αὐτοὺς ῥίζαν — preposition, article, infinitive, accusative subject. Luke and Paul use this constantly, which is one reason their prose can feel dense.
For the reader, the practical skill is recognizing the preposition + τό/τῷ/τοῦ + infinitive pattern and reading it as a unit: cause, purpose, or time. Once the pattern is automatic, long Greek sentences open up. The grammar carries the logical relationship; the surrounding argument supplies the content.
- An infinitive is a verbal noun: it has aspect and voice but no person, number, or mood.
- Key forms: present λύειν, aorist λῦσαι / λυθῆναι, and εἶναι (of εἰμί). The aorist infinitive takes no augment.
- Complementary infinitive completes verbs like δύναμαι, θέλω, μέλλω.
- The articular infinitive (prep + article + inf) forms a clause: cause, purpose, or time. Its subject, if expressed, is accusative; negate with μή.
- Memorize 2nd-aorist and μι-verb infinitives as principal parts; do not derive them.