Infinitivesverbal nouns; complementary & articular
An infinitive is a non-finite verbal form with important nominal functions — "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.
Parse the infinitive before assigning its clause function
CoreMental Map: From Infinitive Form to Meaning
Use the same pathway every time. The goal is not to guess an English gloss from one ending, but to connect morphology, construction, sentence role, and contextual translation.
1. Where Lesson 26 fits in the Greek system
Earlier verb lessons supplied the tense and voice building blocks. The infinitive now packages those verbal ideas inside larger clauses.
2. Recognition decision tree
Move from visible evidence toward meaning. Do not skip the construction step.
3. Keep sentence roles visually stable
These colors will retain the same meaning whenever this mapping system is extended to another lesson.
4. Contrast the forms most likely to be confused
5. Trace form → parse → role → translation
6. Guided annotation transfer
Read each Greek line first. Open the annotation only after you have identified the infinitive and its frame.
δεῖ τὸν δοῦλον λυθῆναι.
δεῖ = impersonal controlling verb · τὸν δοῦλον = accusative subject of the infinitive · λυθῆναι = aorist passive infinitive.
Translation: “It is necessary for the servant to be released.”
ἐν τῷ λέγειν αὐτὸν οἱ μαθηταὶ ἤκουον.
ἐν τῷ frames a dative articular infinitive · λέγειν supplies the event · αὐτόν is its accusative subject.
Translation: “While he was speaking, the disciples were listening.”
μετὰ τὸ λῦσαι τὸν δοῦλον ὁ κύριος ἦλθεν.
μετὰ τὸ frames an accusative articular infinitive · λῦσαι supplies a perfective event · τὸν δοῦλον is its object.
Translation: “After releasing the servant, the Lord came.”
The Learning Lab adds ten questions that ask exactly where a student's parsing pathway broke down.
CorePart 1: What an Infinitive Is
An infinitive is a non-finite verbal form that can occupy several noun-like positions — "to loose," "to believe." It presents a verbal idea without encoding person or number. It carries tense-form/aspect and voice, while its syntactic construction supplies its function.
Because it can function nominally, 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 remains verbal, 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 state-oriented or resultative. 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.