Avus meminit se olim magnum gregem habuisse et cum pastore per prata ambulavisse.

Because Latin often uses an indirect statement instead of a that-clause.

Here, the content of what the grandfather remembers is expressed by:

• se ... habuisse
• et ... ambulavisse

That is the Latin way of saying that he had had ... and had walked ...

So after meminit, Latin does not need a separate word meaning that here.

Se is the accusative reflexive pronoun, and it refers back to the subject of the main verb, avus.

So:

• avus meminit se ... habuisse = the grandfather remembers that he himself had had ...

Latin uses se because the person remembered inside the indirect statement is the same person as the subject of meminit.

If it referred to some other male person, Latin would use something like eum, not se.

Because in a Latin indirect statement, the subject of the infinitive goes into the accusative.

So in:

• se ... habuisse
• se ... ambulavisse understood

the infinitives habuisse and ambulavisse need an accusative subject, and that subject is se.

This is a very common Latin pattern:

• main verb of saying, thinking, knowing, remembering, perceiving, etc.
• then accusative + infinitive

Because they are part of the indirect statement after meminit.

In English, we would normally use finite verbs in a clause:

• he remembers that he had a large flock and walked through the meadows

But Latin usually uses infinitives in this construction:

• se ... habuisse
• et ... ambulavisse

So the infinitives are not random; they are exactly what the indirect statement requires.

They are perfect infinitives because the actions are earlier than meminit.

The idea is:

• now, the grandfather remembers
• earlier, he had the flock
• earlier, he walked through the meadows

So Latin marks those remembered actions as already completed relative to the remembering.

Very roughly:

• meminit = remembers
• habuisse = to have had
• ambulavisse = to have walked

In natural English, we may simplify the translation, but the Latin tense relation is still important.

Because one accusative subject can be shared by both infinitives.

So Latin understands:

• se ... habuisse
• et se ... ambulavisse

but the second se is omitted because it would be repetitive.

This is very normal Latin style. The single se belongs with both actions.

Gregem is accusative singular, because it is the direct object of habuisse.

He remembered that he had had a large flock, so flock is the thing had.

Magnum agrees with gregem:

• same case: accusative
• same number: singular
• same gender: masculine

So:

• grex = flock, herd
• gregem = accusative singular
• magnum gregem = a large flock

Because the two prepositions take different cases and express different ideas.

• cum pastore

  • cum takes the ablative
  • pastore is ablative singular
  • meaning: with the shepherd

• per prata

  • per takes the accusative
  • prata is accusative plural
  • meaning: through the meadows

So the cases are determined by the prepositions.

Olim is an adverb meaning something like:

• once
• formerly
• long ago

Here it signals that the remembered events belong to an earlier time in the past.

So se olim magnum gregem habuisse means that he remembers having had a large flock at one time in the past.

No. In classical Latin, pastor means shepherd or herdsman.

It is related in origin to the English word pastor, but in this sentence the meaning is plainly the literal rural one: someone connected with grazing animals.

So cum pastore means with the shepherd.

Prata is the accusative plural of pratum, meaning meadow.

Because it follows per, it appears in the accusative plural:

• per prata = through the meadows

It is a neuter plural noun.

Et joins the two infinitive phrases inside the indirect statement:

• se olim magnum gregem habuisse
• et cum pastore per prata ambulavisse

So the grandfather remembers two connected things:

1. that he once had a large flock
2. that he walked through the meadows with the shepherd

The et simply coordinates those two remembered actions.

The basic grammar is important, but the exact word order is fairly flexible in Latin.

This sentence puts the main verb first:

• Avus meminit

Then it gives the remembered content.

Some word order choices are especially natural:

• magnum gregem keeps adjective and noun together
• cum pastore stays with ambulavisse
• per prata also belongs closely with ambulavisse

Latin uses word order more freely than English, so another arrangement could still be grammatical, but this order is clear and natural.