Mater annulum in cista deponit, ne infans eum capiat.

Mater is the subject of the sentence, so it is in the nominative singular.

A native English speaker may not notice this right away because English usually depends more on word order than on endings. In Latin, the ending helps show the job a word is doing.

• mater = mother
• nominative singular = the person doing the action

So mater ... deponit means the mother puts/places.

Because annulum is the direct object of deponit.

The mother is putting the ring, so ring receives the action. In Latin, a direct object usually goes in the accusative case.

• annulus = nominative singular, ring as subject
• annulum = accusative singular, ring as object

So:

• annulus deponit would mean the ring puts down..., which makes no sense here
• mater annulum deponit means the mother puts down the ring

Here cista is ablative singular, so in cista means in the box.

The basic textbook rule is:

• in
  • ablative = in/on a place
• in
  • accusative = into a place

So a learner might expect in cistam if the emphasis is on movement into the box.

Why, then, do we see in cista here? Because with verbs of placing or putting, Latin can sometimes focus on the resulting location rather than the movement itself. So in cista deponit can naturally mean putting it in the box, with attention on where it ends up.

So the useful takeaway is:

• the basic rule still matters
• but real Latin usage can be a little more flexible than the first rule you learn

Deponit comes from deponere, which literally means something like put down, set down, place, or put away.

In context, it often has the sense of placing something somewhere, sometimes carefully or deliberately. So depending on the English translation, you might see:

• puts the ring in the box
• places the ring in the box
• puts the ring away in the box

It is present tense, third person singular, active voice:

• deponit = she puts / she is putting

Ne introduces a negative purpose clause.

That means it shows the purpose of the main action, but in a negative way:

• ut = so that
• ne = so that ... not

So ne infans eum capiat means so that the child does not take it or more naturally so that the baby won’t get it.

A more formal English translation could also use lest:

• lest the child take it

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

So:

• capit = indicative, takes
• capiat = present subjunctive, used here because the clause expresses purpose

The structure is:

• main clause: Mater annulum in cista deponit
• purpose clause: ne infans eum capiat

The mother puts the ring in the box for the purpose of preventing the child from taking it.

That is why Latin uses the subjunctive rather than the ordinary indicative.

This is because of the normal sequence of tenses in Latin.

The main verb deponit is a present tense, which counts as a primary tense. After a primary tense, a purpose clause usually takes the present subjunctive.

So:

• deponit = present indicative
• capiat = present subjunctive

If the main verb were in a past tense, Latin would usually use the imperfect subjunctive instead:

• Mater annulum in cista deposuit, ne infans eum caperet.

So the tense choice is grammatical, not random.

Eum is a pronoun meaning him/it, and here it refers back to annulum.

Latin often uses a pronoun to avoid repeating a noun, just as English does. Since annulus is masculine singular, the pronoun must match it:

• eum = masculine singular accusative

It is accusative because it is the object of capiat.

So:

• annulum = the ring
• eum = it, referring to the ring

A learner may also wonder why it is not id. The answer is that id would be neuter, but annulus is masculine, so eum is the correct agreement.

Infans is a third-declension noun meaning infant, baby, or young child.

Its grammatical gender can depend on the actual child being referred to. It is often treated as a noun that can refer to either a male or female child. In this sentence, nothing in the form infans itself tells you whether the child is a boy or a girl.

What matters here is its case and role:

• infans is nominative singular
• it is the subject of capiat

So infans capiat means the child may take.

Latin word order is more flexible than English word order because the endings show the grammatical roles.

So this sentence does not depend on word order as heavily as an English sentence would. The current order is natural and clear:

• Mater — subject first
• annulum — object
• in cista — place
• deponit — verb
• then the purpose clause

But Latin could rearrange parts for emphasis. For example, moving eum or in cista would change emphasis, not the basic meaning.

A useful principle is:

• in English, word order often shows grammar
• in Latin, endings show grammar, and word order often shows emphasis

Yes. That is a very traditional and often very accurate way to translate it.

So you could render the clause as:

• so that the child does not take it
• lest the child take it

For many modern learners, so that ... not is easier to understand at first. But knowing lest is helpful, because it often appears in grammar explanations for ne clauses.

Latin does not have a definite article like English the, or an indefinite article like a/an.

So:

• mater can mean mother or the mother
• annulum can mean a ring or the ring
• infans can mean a child or the child

You figure out the most natural English wording from the context. In this sentence, English usually wants the mother, the ring, the box, and the child, but Latin does not need separate words for that.