Pater librum in scrīniō pōnit, nē infāns eum capiat.

Because librum is the direct object of pōnit.

• pater = the father
• pōnit = places, puts
• librum = the book

The direct object is the thing being acted on, so Latin puts it in the accusative case.

Dictionary form: liber
Accusative singular: librum

Because in can take two different cases depending on the meaning:

• in + ablative = in / on a place, showing location
• in + accusative = into / onto a place, showing motion toward

Here, in scrīniō means in the box/case/cabinet, emphasizing where the book ends up.

So:

• in scrīniō = in the chest/case
• in scrīnium would mean into the chest/case

In many contexts English just says puts the book in the box, but Latin still marks the distinction with the case.

Scrīnium is a neuter noun meaning something like a case, box, chest, book box, or cabinet for papers/books.

In this sentence, in scrīniō suggests that the father puts the book into a container or storage place so the child cannot get it easily.

Nē introduces a negative purpose clause.

A purpose clause tells why someone does something.
So:

• ut = so that
• nē = so that not / lest

Here:

• Pater librum in scrīniō pōnit = The father puts the book in the case
• nē infāns eum capiat = so that the child may not get it

So nē is not just a simple not. It means in order that ... not or lest.

Because after nē in a purpose clause, Latin normally uses the subjunctive mood.

So:

• capit = he/she gets, takes
• capiat = he/she may get, might get, would get in this purpose idea

The clause nē infāns eum capiat is not simply stating a fact. It expresses the father's purpose or intention:

• He puts the book away
• so that the child will not get it

That is why capiat is subjunctive.

Capiat is the present subjunctive active, 3rd person singular, of capiō, capere.

This verb is a 3rd-conjugation -iō verb. Its present subjunctive uses -ia- before the personal ending:

• capiam
• capiās
• capiat
• capiāmus
• capiātis
• capiant

So capiat means may get, may take, or in smoother English here, might get.

Because infāns is the subject of capiat.

In the clause nē infāns eum capiat:

• infāns = the child/infant
• eum = him/it
• capiat = may get/take

The child is the one doing the action of getting the book, so infāns is in the nominative case.

A learner may expect infāntem, but that would be accusative, and here the child is not the object.

Eum means him or it, and here it refers back to librum.

Since liber is a masculine noun, the pronoun that refers to it must also be masculine:

• nominative: is
• accusative: eum

So:

• librum = the book
• eum = it, referring to the book

Latin often uses a pronoun like this instead of repeating the noun.

In Latin, there is no separate everyday personal pronoun that works exactly like English it. Instead, Latin uses the regular 3rd-person pronouns, which change according to gender.

Because liber is masculine, Latin uses the masculine form:

• eum = him/it for a masculine object

If the noun were neuter, a neuter pronoun would be used instead.

So eum may look like him, but in this sentence it simply means it, referring to the book.

Latin word order is much more flexible than English word order because Latin uses case endings to show each word’s role in the sentence.

English relies heavily on word order:

• The father puts the book in the case

Latin can move words around more freely:

• Pater librum in scrīniō pōnit
• Librum pater in scrīniō pōnit
• In scrīniō pater librum pōnit

These all mean roughly the same thing, though the emphasis may change.

In your sentence, the order is very natural:

• pater first: topic or subject
• librum next: the thing being moved
• in scrīniō: where it is put
• pōnit at the end: a very common place for the verb in Latin

The main verb pōnit is present tense, and the subordinate verb capiat is present subjunctive because Latin normally uses the present subjunctive after a primary tense in purpose clauses.

This is part of what is often called sequence of tenses:

• main verb in a primary tense, such as present → purpose clause usually takes present subjunctive

So:

• pōnit = he puts
• capiat = so that the child may not get it

Even though English might translate the sense as future-looking, Latin still uses the present subjunctive here because it is the normal form after a present-tense main verb.

Yes. That is a very traditional and accurate translation.

Possible English translations include:

• so that the child may not get it
• so that the child does not get it
• lest the child get it

Lest is often the neatest one-word equivalent of nē in this kind of sentence, though it sounds formal or old-fashioned in modern English.

It can mean more than just a tiny baby. Infāns literally means not speaking, and it can refer to an infant, young child, or sometimes simply a child depending on context.

So in this sentence, infāns could be understood as:

• the baby
• the infant
• the child

The exact age is not the main point; the point is that the father is keeping the book away from someone too young to be trusted with it.