Pater vult a philosopho Graeco audiri, itaque quaestionem clare proponit.

Because audiri is the present passive infinitive of audire.

• audire = to hear
• audiri = to be heard

So:

• Pater vult audire = The father wants to hear
• Pater vult audiri = The father wants to be heard

That passive form is essential to the meaning of this sentence.

Vult means he wants, and it is followed by an infinitive.

Latin often uses:

• volo + infinitive = to want to ...

So here:

• vult audiri = he wants to be heard

The understood subject of audiri is the same as the subject of vult, namely pater. In other words, the sentence means the father wants himself to be heard.

Because with a passive verb, the person doing the action is often expressed by a/ab + ablative.

Here:

• audiri = to be heard
• the one doing the hearing is the Greek philosopher
• so Latin says a philosopho Graeco = by the Greek philosopher

This is called the ablative of personal agent.

Both a and ab mean by before an ablative of agent. The choice usually depends on sound:

• ab is common before vowels and often before consonants too
• a is especially common before consonants

Since philosopho begins with a consonant sound, a philosopho is perfectly normal.

Because Graeco is an adjective modifying philosopho, and adjectives must agree with the nouns they describe in:

• case
• number
• gender

So:

• philosopho = ablative singular masculine
• Graeco = ablative singular masculine

Together they mean by the Greek philosopher.

Quaestionem is accusative singular.

It is the direct object of proponit:

• proponit = he sets forth / presents / proposes
• What does he present? quaestionem = the question

So the accusative is used because it receives the action of the verb.

Clare is an adverb, meaning clearly.

It modifies proponit:

• proponit = he presents
• clare proponit = he presents clearly / he clearly sets forth

This tells us how he presents the question.

Itaque means and so, therefore, or thus.

It connects the two parts of the sentence:

1. Pater vult a philosopho Graeco audiri
2. itaque quaestionem clare proponit

The logic is:

• The father wants to be heard by the Greek philosopher,
• so he states the question clearly.

In both clauses, the main subject is pater.

1. Pater vult ... audiri

   • pater is the one who wants
   • pater is also the one who is to be heard

2. quaestionem clare proponit

   • the understood subject of proponit is again pater
   • so he presents the question clearly

Meanwhile, a philosopho Graeco tells us who would do the hearing.

Because Latin very often leaves the subject pronoun unspoken when the verb ending already shows the person.

• proponit = he/she/it presents

Since pater has already been named, Latin does not need to repeat is or another pronoun. The subject is understood from context.

The word order is flexible, but not unusual for Latin.

A very literal order would be:

• Father wants by the Greek philosopher to-be-heard, and so the question clearly he-presents.

Latin often places:

• the main verb early or late for emphasis,
• modifiers near the words they belong to,
• the infinitive after verbs like vult.

So this sentence is quite natural. English depends more on fixed word order, but Latin depends more on endings.

In some contexts, a/ab can mean from, but here the passive infinitive audiri makes the meaning clearly by.

With a passive verb, a/ab + ablative commonly marks the agent:

• audiri a philosopho Graeco = to be heard by the Greek philosopher

So in this sentence, by is the natural interpretation.

The dictionary verb is audio, audire, audivi, auditum = hear.

Audiri is the present passive infinitive of audire.

For a 4th-conjugation verb like audire:

• active infinitive: audire = to hear
• passive infinitive: audiri = to be heard

That -ri ending is the key sign of the passive infinitive here.

Because Latin normally expresses wanting to do something with volo + infinitive.

So Latin says:

• vult audiri = he wants to be heard

English can also use an infinitive here, so the structure is actually fairly close between the two languages. Latin does not need a separate that-clause in this sentence.