Mater culcitam novam emit, quia vetus nimis dura erat.

Because Latin noun gender and noun ending are not the same thing.

Mater is a feminine noun, but it belongs to the third declension, not the first declension. So its nominative singular form is mater, not something ending in -a.

In this sentence, mater is the subject, so it is in the nominative singular.

Because culcitam is the direct object of emit.

The sentence says that mother bought the new cushion/mattress/pillow—that is the thing receiving the action of buying. In Latin, a direct object usually goes in the accusative case.

So:

• culcita = nominative singular
• culcitam = accusative singular

The -am ending shows that this noun is accusative singular.

Because adjectives in Latin must agree with the nouns they describe in:

• gender
• number
• case

Here novam describes culcitam, so it must match it:

• culcitam = feminine, singular, accusative
• novam = feminine, singular, accusative

That is why both words have accusative singular feminine endings.

This is a very common beginner question, because without macrons the form can look ambiguous.

From emere:

• emit can be present: he/she buys
• ēmit can be perfect: he/she bought

If macrons are written, the difference is clear:

• emit = buys
• ēmit = bought

If macrons are not written, you use context and the given meaning. In this sentence, the intended meaning is the perfect, so emit is understood as bought.

Because Latin often allows an adjective to be used substantively, meaning that the noun is understood rather than stated.

So vetus here means something like:

• the old one
• the old cushion/mattress/pillow

The noun does not need to be repeated because it is already clear from culcitam novam in the first clause.

This is very natural in Latin.

Because dura agrees with the understood noun behind vetus.

Even though the noun is omitted, Latin still treats it as present in sense. The implied noun is culcita, which is feminine singular. So the adjective must also be feminine singular:

• durus = masculine
• dura = feminine
• durum = neuter

So vetus nimis dura erat means the old one was too hard, with dura agreeing with the implied feminine noun.

Because vetus is a third-declension adjective, and its nominative singular form is the same for masculine, feminine, and neuter.

So:

• masculine: vetus
• feminine: vetus
• neuter: vetus

That is why vetus does not visibly show feminine gender here. The feminine idea is shown instead by dura, which has a distinct feminine form.

Nimis is an adverb meaning too or too much.

Here it modifies dura:

• dura = hard
• nimis dura = too hard

So it tells you the degree of hardness.

Because the sentence is describing a state in the past, not a single completed action.

Erat means was, and the imperfect tense is often used for background description or an ongoing condition in the past. The idea is:

• the buying happened as an event: emit / ēmit
• the old one’s hardness was a continuing condition: erat

So erat fits the sense very well: the old one was too hard.

Because Latin word order is much more flexible than English word order.

English depends heavily on position:

• Mother bought a new mattress

Latin depends much more on endings, so the words can be arranged more freely without changing the basic meaning.

In this sentence:

• Mater comes first for the subject
• culcitam novam stays together as noun + adjective
• emit comes at the end of the main clause, which is very common in Latin
• the quia clause comes after it to give the reason

So the order is normal and natural for Latin, even though it is not the most natural order in English.