Pater librum in scrinio ponit, ne infans eum capiat.

Here is the basic breakdown:

• Pater: nominative singular
  
  • the subject of ponit
• librum: accusative singular
  
  • the direct object of ponit
• scrinio: ablative singular
  
  • used with in
• infans: nominative singular
  
  • the subject of capiat
• eum: accusative singular
  
  • the direct object of capiat

And the verbs are:

• ponit: he puts, present active indicative, 3rd person singular
• capiat: may take / might take, present active subjunctive, 3rd person singular

So the sentence is built as:

Father puts the book in the desk/case, so that the baby may not take it.

Because it is the direct object of ponit.

The verb ponere means to put / place, and the thing being put is the direct object. In this sentence, the father is putting the book, so liber becomes librum.

A native English speaker can think of it this way:

• Pater = who is doing the action
• librum = what is being acted on

That is a very common accusative use in Latin.

That is a very sensible question, because the beginner rule is:

• in + accusative = motion into
• in + ablative = location in

So many learners would expect in scrinium with ponit.

In actual Latin, however, with verbs of placing such as ponere, writers can use in + ablative when the emphasis is on the resulting location: in the desk/case, rather than on the motion into it.

So:

• in scrinium ponit = emphasizes motion into
• in scrinio ponit = emphasizes where the book ends up

Both ideas are very close in meaning here. The sentence you were given focuses on the book’s position once it has been put away.

Here ne introduces a negative purpose clause.

So ne infans eum capiat means:

• so that the baby may not take it
• or more literally, lest the baby take it

In Latin:

• ut often introduces a positive purpose clause: so that
• ne introduces a negative purpose clause: so that ... not

So the father puts the book away for the purpose of preventing the baby from taking it.

Because it is inside a purpose clause introduced by ne.

Latin normally uses the subjunctive in purpose clauses. So after ne, you expect a subjunctive verb:

• ne ... capiat = so that ... may not take

If the sentence had used the indicative, it would not sound like a normal purpose clause.

So the contrast is:

• ponit = indicative, because this is the main action and is presented as a fact
• capiat = subjunctive, because it expresses the intended result/purpose

Because the main verb is present: ponit.

This follows the usual sequence of tenses for purpose clauses:

• after a primary tense such as ponit, Latin commonly uses the present subjunctive
• after a past tense such as posuit, Latin commonly uses the imperfect subjunctive

So:

• Pater librum ... ponit, ne infans eum capiat.
• Pater librum ... posuit, ne infans eum caperet.

That is why capiat is the form used here.

Eum refers to librum.

The noun liber is masculine, so the pronoun referring back to it must also be masculine singular. That is why Latin uses eum, not id.

Also, the pronoun is the direct object of capiat, so it must be in the accusative:

• masculine singular accusative = eum

A useful rule is:

• pronouns agree with their antecedent in gender and number
• but their case depends on their role in their own clause

So eum is:

• masculine singular, to match librum
• accusative, because it is what the baby might take

Because Latin does not have articles like English does.

So a noun like pater can mean:

• father
• a father
• the father

and librum can mean:

• a book
• the book

Context tells you which is most natural.

If Latin wants to be more specific, it can use words such as hic, ille, or is, but it often does not need to.

Latin word order is much freer than English word order, because case endings show the grammatical roles.

So the basic meaning would stay the same even if the sentence were rearranged. But the order chosen here is natural and useful:

• Pater first: the doer of the action
• librum early: the important object
• in scrinio next: where it is put
• ne infans eum capiat after that: the reason or purpose
• capiat at the end: very common Latin placement for emphasis and closure

So yes, the order can change, but the given order is quite normal and readable.

Not in the English military sense.

The verb capere has a broad range of meanings, including:

• take
• seize
• grab
• catch
• capture

In this sentence, with a baby and a book, the natural meaning is take or grab.

So ne infans eum capiat is best understood as:

• so that the baby does not take it
• or so that the baby cannot get hold of it

For a negative purpose clause, Classical Latin normally prefers ne, not ut ... non.

So:

• ne infans eum capiat = so that the baby may not take it

By contrast, ut ... non is more naturally used for other kinds of clauses, especially negative result clauses.

So in a sentence of purpose like this one, ne is the standard choice.

Infans is a 3rd-declension noun.

In this sentence it is nominative singular, because it is the subject of capiat.

It literally means not speaking, and from that it came to mean infant, baby, or young child. It can refer to a male or female child depending on context, so the form itself does not tell you the baby’s sex here.

What matters grammatically in this sentence is simply that infans is the subject of the subordinate clause.