Auriga currum lente agit, ne axis frangatur.

Because auriga is the subject of agit. It is the person doing the action: the charioteer is driving.

Even though auriga ends in -a, it is masculine here and belongs to the first declension. That can surprise English speakers, since many first-declension nouns are feminine, but some nouns referring to male professions or roles, such as auriga and nauta, are masculine.

Because currum is the direct object of agit. It is the thing being driven.

So:

• auriga = the driver
• agit = drives
• currum = the chariot, as the object of drives

That is why currus becomes currum here.

Lente is an adverb, meaning slowly. It modifies the verb agit, telling us how the charioteer drives.

If you used lentus, lenta, or lentum, those would be adjective forms meaning slow and would describe a noun, not a verb. Here Latin needs an adverb because the sentence is talking about the manner of driving.

So:

• lentus auriga = a slow charioteer
• lente agit = he drives slowly

Here agit means drives. The basic verb agere has a broad range of meanings, such as to drive, to do, to lead, or to set in motion, depending on context.

With currum, agere commonly means to drive a chariot. So currum agit is a natural Latin expression for he drives the chariot.

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

This sentence could be rearranged in several ways without changing the basic meaning, for example:

• Auriga currum lente agit
• Currum auriga lente agit
• Lente auriga currum agit

The usual effect of changing the order is not to change who does what to whom, but to shift emphasis or style. In the given sentence, the order is straightforward and natural.

Here ne means so that ... not or lest. It introduces a negative purpose clause.

So ne axis frangatur means:

• so that the axle may not be broken
• more naturally in English: so that the axle does not break or lest the axle break

This is different from non, which usually just negates a word or statement directly. Ne is commonly used with the subjunctive in purpose clauses.

It is a negative purpose clause.

The main clause is:

• Auriga currum lente agit = the charioteer drives the chariot slowly

The purpose clause explains why he does so:

• ne axis frangatur = so that the axle may not be broken

In other words, he drives slowly in order to prevent the axle from breaking.

Because Latin normally uses the subjunctive in purpose clauses introduced by ut or ne.

Since ne axis frangatur expresses purpose, frangatur must be subjunctive. The main clause gives the action; the subordinate clause gives the intended result or goal.

So the pattern is:

• ut
  • subjunctive = positive purpose
• ne
  • subjunctive = negative purpose

Because the verb frangere means to break something, so in Latin it is normally transitive. If the axle is the thing receiving the action, Latin naturally says the axle is broken rather than using an active form meaning the axle breaks.

So:

• active: aliquis axem frangit = someone breaks the axle
• passive: axis frangitur = the axle is broken

In English, we often say the axle breaks, but Latin often expresses that idea with the passive of frangere.

Because axis is the subject of frangatur.

Even though the overall sentence begins with auriga as the subject of the main clause, the subordinate clause ne axis frangatur has its own subject: axis.

So the structure is:

• main clause subject: auriga
• subordinate clause subject: axis

That is why axis is nominative.

Frangatur is present subjunctive passive, third person singular.

In a purpose clause after a present main verb like agit, the present subjunctive is normal. It does not mean strictly is being broken here. Instead, it expresses the intended outcome:

• ne axis frangatur = so that the axle may not be broken
• more natural English: so that the axle does not break

So the Latin tense is present, but in English the best translation often depends on idiom rather than on matching the tense mechanically.

Yes. Latin axis can mean axle or axis, and it is the source of the English word axis.

In this sentence it means axle, the rod on which the wheels turn. That fits the chariot context: the driver goes slowly so the axle will not break.