Coepi: To Begin | Latin Grammar

Coepī means “I began” or “I have begun.” Its principal parts are coepī, coepisse, coeptum. It is defective: Classical prose regularly uses only perfect-system forms and the forms built on coept-. For a present “I begin,” Latin normally uses incipiō. The missing present system is not an invitation to create coepiō or coepō.

Unlike nōvī, perfect-shaped coepī has ordinary past or completed meaning. The two verbs are alike only in lacking a full present system. This distinction matters because “defective” describes missing forms, not one universal tense shift.

How to Parse Coepī

Begin with the ending. The stem coep- plus perfect endings gives active “began”; the participial stem coept- plus a form of sum gives a passive construction or a construction aligned with a passive infinitive.

Visible form	Parse	Normal value
coepit	perfect active indicative, 3rd singular	“he/she/it began”
coeperat	pluperfect active indicative, 3rd singular	“he/she/it had begun”
coeperit	future perfect indicative or perfect subjunctive	“will have begun” or “may have begun”
coepta est	perfect passive, feminine singular	“was begun” or “began to be …”

Senātor dīcere coepit, sed clāmor eum interrūpit.

The senator began to speak, but shouting interrupted him.

Cum ad portum vēnimus, tempestās iam coeperat.

When we reached the harbor, the storm had already begun.

Ubi lūcēscere coeperit, proficīscēmur.

When it has begun to grow light, we shall set out.

English often prefers simple “when dawn begins.” Latin future perfect looks back on the beginning from the future departure. Translate the relationship, not each tense label in isolation.

Complete Active Finite Paradigm

Tense	1st sg.	2nd sg.	3rd sg.	1st pl.	2nd pl.	3rd pl.
perfect indicative	coepī	coepistī	coepit	coepimus	coepistis	coepērunt / coepēre
pluperfect indicative	coeperam	coeperās	coeperat	coeperāmus	coeperātis	coeperant
future perfect indicative	coeperō	coeperis	coeperit	coeperimus	coeperitis	coeperint
perfect subjunctive	coeperim	coeperīs	coeperit	coeperīmus	coeperītis	coeperint
pluperfect subjunctive	coepissem	coepissēs	coepisset	coepissēmus	coepissētis	coepissent

The shortened perfect coepēre is (literary). There is no ordinary present, imperfect, or future active paradigm. For those time frames use incipiō: incipit “he begins,” incipiēbat “he was beginning,” incipiet “he will begin.” A present coepiō has early or exceptional evidence (archaic), but it is not a productive Classical paradigm and should not replace neutral incipiō.

Nōndum labōrāre coeperāmus cum nūntius advenit.

We had not yet begun to work when the messenger arrived.

Nesciō cūr rīdere coeperint.

I do not know why they began to laugh.

In the second example, the indirect question requires coeperint as perfect subjunctive. The form is identical to the third-person plural future perfect indicative; clause structure decides.

The Coeptus Sum Construction

When coepī governs an active infinitive, the active form is normal: puerī currere coepērunt “the boys began to run.” When the dependent infinitive is passive, Classical prose commonly makes coepī itself passive and agrees its participle with the subject of that infinitive: liber legī coeptus est, literally “the book was begun to be read.” Natural English says “the book began to be read.”

Epistula ante noctem scrībī coepta est.

The letter began to be written before nightfall.

Mūrī ab operāriīs reficī coeptī sunt.

The walls began to be repaired by the workers.

The agreement is visible: feminine singular epistula ... coepta est; masculine plural mūrī ... coeptī sunt. This is not an arbitrary ornament. The passive infinitive’s patient becomes the grammatical subject of the whole expression.

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With an active infinitive, expect active coepit. With a passive infinitive and an expressed patient, actively look for agreeing coeptus est. Parse the agreement before translating the idiom.

The full passive system is therefore periphrastic rather than a set of synthetic forms:

Finite value	Pattern	Example, masculine singular
perfect indicative	coeptus, -a, -um + present sum	coeptus est
pluperfect indicative	coeptus, -a, -um + imperfect sum	coeptus erat
future perfect indicative	coeptus, -a, -um + future sum	coeptus erit
perfect subjunctive	coeptus, -a, -um + present subjunctive sum	coeptus sit
pluperfect subjunctive	coeptus, -a, -um + imperfect subjunctive sum	coeptus esset

Gender and number change with the subject: coepta est, coeptum est, coeptae sunt, coepta sunt. An impersonal neuter coeptum est can mean “a beginning was made” (formal), but learners should not use it to erase agreement when a clear plural subject is present.

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When you meet coept- plus sum, look outward for a nominative patient and make the participle agree with it. The passive infinitive that follows remains invariant.

Pōns reficī coeptus erat, sed pecūnia dēfuit.

The bridge had begun to be repaired, but the money ran out.

Non-Finite Forms and Complement Syntax

Category	Form and status
perfect active infinitive	coepisse, “to have begun”
perfect passive infinitive	coeptum, -am, -um esse, “to have been begun”
perfect passive participle	coeptus, -a, -um, “begun”
future active participle	coeptūrus, -a, -um, rare (formal/literary)
future active infinitive	coeptūrum esse, rare (formal/literary)
supine	coeptum, chiefly preserved as the principal-part form
present infinitive, participle, gerund	absent; use forms of incipiō where needed

The usual complement is a present infinitive whose understood subject is the subject of coepī: scrībere coepit “she began to write.” This infinitive describes the activity entering its initial phase, not a purpose.

Dīcit sē novum librum scrībere coepisse.

She says that she has begun to write a new book.

Here sē is the accusative subject of both coepisse and understood scrībere. For more on shared subjects, see Complementary Infinitives.

Coepī can also occur without an expressed infinitive when the action is recoverable: tempestās coepit “the storm began.” It does not govern a special object case. A noun naming an undertaking may instead be the subject of passive coeptus est.

Lūdus post Kalendās coeptus est.

The festival was begun after the Kalends.

Compounds and Lexical Alternatives

Classical Latin does not freely build a productive family of compounds on defective coepī. Incipiō, incipere, coepī, inceptum supplies the missing present system and is the ordinary alternative “begin, undertake.” Its perfect coepī is historically and synchronically shared with this defective entry. Inchoō “begin, initiate” is another full verb, especially when beginning a project (formal).

This suppletion-like division is the practical rule: produce present-system meanings with incipiō, but recognize the bare perfect-system forms of coepī. Do not attach prefixes to coepī as if it were an independent productive stem.

Common Mistakes

Inventing a present form

❌ Nunc labōrāre coepiō.

Incorrect — coepī has no regular present coepiō.

✅ Nunc labōrāre incipiō.

I am beginning to work now.

Shifting coepī to present meaning like nōvī

❌ Coepī epistulam scrībere.

Incorrectly translated ‘I am beginning to write a letter’ — coepī is perfect and means ‘I began / have begun.’

✅ Coepī epistulam scrībere.

I began to write a letter.

Ignoring agreement with a passive infinitive

❌ Domus reficī coeptum est.

Incorrect with singular feminine domus as the expressed subject.

✅ Domus reficī coepta est.

The house began to be repaired.

Using a finite clause where a complementary infinitive is required

❌ Coepit quod clāmābat.

Incorrect for ‘he began to shout’ — quod does not introduce the activity begun.

✅ Clāmāre coepit.

He began to shout.

Key Takeaways

Coepī, coepisse, coeptum has a perfect system but no ordinary present system.
Use incipiō for present, imperfect, and future “begin.”
With active infinitives, use active coepī; with passive infinitives, expect agreeing coeptus est.
Coepisse and coeptum esse provide the chief non-finite forms; rarer future forms need context and register awareness.

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