Post imbrem puella muscum tangit et dicit eum molliorem esse quam herbam siccam.

Because post is a preposition that takes the accusative case when it means after. The dictionary form is imber (rain, rainstorm), but the accusative singular is imbrem.

So:

• imber = nominative, dictionary form
• imbrem = accusative, used after post

That is why post imbrem means after the rain.

Because muscum is the direct object of tangit. The girl is doing the action of touching, and the moss is what she touches.

So:

• puella = the subject, the girl
• tangit = touches
• muscum = the direct object, the moss

The dictionary form is muscus, but as a direct object it becomes muscum.

Both are 3rd person singular present active indicative.

• tangit = she touches
• dicit = she says

They are 3rd person singular because the subject is puella, which is singular: the girl.

Latin often does not need to include a separate word for she, because the verb ending already shows it.

This is a very common Latin construction called an indirect statement or accusative-and-infinitive construction.

English usually says:

• she says that it is softer

Latin often says:

• she says it to be softer

That is why you get:

• dicit = she says
• eum = it as the subject of the indirect statement
• esse = to be
• molliorem = softer

So dicit eum molliorem esse literally means she says it to be softer, which is the normal Latin way to express she says that it is softer.

Eum refers to muscum.

It is masculine singular accusative, because:

1. muscus is a masculine noun.
2. In an indirect statement, the subject of the infinitive is put in the accusative.

So:

• muscus = masculine
• eum = him/it in masculine accusative singular

Here it means it, referring to the moss.

Molliorem is the comparative adjective meaning softer.

Its basic forms are:

• mollis = soft
• mollior = softer for masculine/feminine
• mollius = softer for neuter

In this sentence, molliorem is masculine accusative singular because it goes with eum, which is also masculine accusative singular.

So the grammar is:

• eum = accusative singular
• molliorem = accusative singular to match it
• esse = infinitive

Together: eum molliorem esse = it to be softer

With quam in a comparison, Latin often puts the second thing being compared in the same case as the first.

Here the first thing is eum, which is accusative because it is the subject of the indirect statement. So the second thing, herbam siccam, is also accusative after quam.

So:

• eum molliorem esse = it to be softer
• quam herbam siccam = than dry grass

This is why the sentence does not use nominative herba sicca here.

Yes. Latin often has two ways to make a comparison:

1. comparative + quam
2. comparative + ablative

So a Latin speaker could compare things with quam, as in this sentence, or sometimes with the ablative of comparison instead.

The version with quam is often especially clear for learners, because it makes the comparison very explicit.

Both are possible. Latin word order is much more flexible than English word order.

• herbam siccam
• siccam herbam

Both can mean dry grass.

The order in the sentence is a normal, unremarkable one. Latin authors may move adjectives around for emphasis, rhythm, or style, but the endings tell you which words go together.

The word order is fairly natural Latin, but it is not fixed in the way English word order is.

Here is the structure:

• Post imbrem = time phrase, after the rain
• puella = subject, the girl
• muscum tangit = touches the moss
• et dicit = and says
• eum molliorem esse quam herbam siccam = indirect statement, that it is softer than dry grass

Latin often puts important setting information first, so post imbrem comes at the beginning. It is also common for verbs like tangit and dicit to come later in their clauses.

Sometimes Latin can omit a pronoun if the meaning is obvious, but here eum is useful because it clearly marks the subject of esse in the indirect statement.

Without eum, the sentence would be less clear, especially because there is another accusative phrase later: herbam siccam.

So eum helps the reader see immediately:

• what is being said about
• namely, the moss

Because siccam agrees with herbam.

The noun herba is feminine, and here it is accusative singular, so the adjective must match it:

• herba = feminine singular
• herbam = feminine accusative singular
• sicca = feminine singular
• siccam = feminine accusative singular

Latin adjectives agree with their nouns in gender, number, and case.

It is a prepositional phrase functioning as a time expression: after the rain.

It tells you when the girl touches the moss and says this about it. It is not the subject or object of the main verbs; it simply sets the scene.

So the core sentence is:

• puella muscum tangit et dicit...

and post imbrem adds the time context.