Magistra dicit ambitionem sine constantia cito cadere.

Because this sentence uses indirect statement after dicit (says).

In Latin, after verbs of saying, thinking, knowing, and perceiving, the thing that would be the subject of the reported statement usually goes into the accusative, and the verb of that reported statement goes into the infinitive.

So instead of saying something like ambitio cito cadit, Latin says:

• dicit ambitionem cito cadere = she says that ambition falls quickly

Here:

• ambitionem = accusative subject of the infinitive
• cadere = infinitive verb of the reported statement

This is often called the accusative-and-infinitive construction.

For the same reason: after dicit, Latin normally uses indirect statement, not a clause with that plus a finite verb.

English says:

• The teacher says that ambition falls quickly.

Latin typically says:

• Magistra dicit ambitionem cito cadere.

So cadere is the infinitive because it belongs to the statement being reported after dicit.

If it were cadit, that would be a normal finite verb, and the sentence structure would be different.

Sine means without, and it takes the ablative case.

So:

• sine = without
• constantia = constancy, steadfastness, or persistence in the ablative singular

That is why it is constantia, not constantiam or constantiās.

A good rule to remember is:

• sine + ablative

Examples:

• sine aqua = without water
• sine amico = without a friend
• sine constantia = without constancy

Cito is an adverb meaning quickly, and it modifies the verb cadere.

So the idea is:

• to fall quickly
• or more naturally in English, depending on context, to fail quickly, to collapse quickly, or to come to ruin quickly

It does not modify dicit here. The sense is not the teacher quickly says; it is the teacher says that ambition quickly falls.

Yes, cadere literally means to fall, but like many Latin verbs, it can also be used more figuratively.

In this sentence, ambitionem ... cadere probably means something like:

• ambition falls
• ambition collapses
• ambition fails
• ambition comes to nothing

Because ambition is abstract, English may prefer a less literal wording, but Latin is perfectly happy using cadere this way.

Because magistra is the feminine form of teacher or female teacher.

Compare:

• magister = male teacher
• magistra = female teacher

So the sentence specifically has a female subject: the teacher (female) says...

Magistra is in the nominative singular, which is the normal case for the subject of a sentence.

Also, dicit is third person singular, so it matches a singular subject:

• magistra = the teacher
• dicit = says

By contrast:

• ambitionem is accusative, so it is not the main subject of dicit
• it is the subject of the infinitive cadere inside the indirect statement

Because Latin usually does not need one in this construction.

English often introduces reported statements with that:

• She says that ambition falls quickly.

Latin usually expresses the same idea with:

• a verb of saying/thinking/etc.
• an accusative subject
• an infinitive verb

So instead of a separate word meaning that, Latin uses the structure itself:

• dicit ambitionem cito cadere

That whole accusative-infinitive phrase functions like that ambition falls quickly.

Yes. Latin word order is much freer than English word order because the case endings show the grammatical relationships.

So all of these would still mean basically the same thing:

• Magistra dicit ambitionem sine constantia cito cadere.
• Magistra ambitionem sine constantia cito cadere dicit.
• Ambitionem magistra sine constantia cito cadere dicit.

However, word order can affect emphasis. The given sentence is a natural and straightforward arrangement:

• Magistra = topic/subject first
• dicit = main verb early
• then the indirect statement follows

Often, yes. Ambitio in Latin can mean ambition, but it can also carry negative shades such as:

• self-seeking
• political canvassing
• unscrupulous ambition
• striving for office or influence

The exact tone depends on context. In this sentence, the idea seems moralizing: ambition without steadiness does not last. So the word may be somewhat negative, or at least cautionary.

It breaks down like this:

• Magistra — nominative singular subject: the teacher
• dicit — main verb: says
• ambitionem — accusative subject of infinitive: ambition
• sine constantia — prepositional phrase: without constancy
• cito — adverb: quickly
• cadere — infinitive: to fall

So the structure is:

• Main clause: Magistra dicit
• Indirect statement: ambitionem sine constantia cito cadere

In other words:

• The teacher says [ambition falls quickly without constancy].

Grammatically, you could imagine that possibility for a moment, but in context it clearly goes with cadere.

The natural sense is:

• ambition falls quickly without constancy

not:

• the teacher says without constancy

Also, sine constantia fits the meaning of ambition much better than the act of saying. So a learner should understand it as part of the reported idea, linked with cadere.

The direct statement would be:

• Ambitio sine constantia cito cadit.
• Ambition falls quickly without constancy.

Then, if you turn that into reported speech after dicit, Latin changes it to indirect statement:

• Magistra dicit ambitionem sine constantia cito cadere.

So the changes are:

• ambitio → ambitionem
• cadit → cadere

That is a very useful pattern to learn.