Si bene valere vis, aquam puram potius quam vinum bibere debes.

Because each infinitive depends on a different finite verb:

• vis valere = you want to be well / healthy
• debes bibere = you ought to drink

This is very common in Latin. Verbs like velle (to want) and debere (to ought / must / should) are often followed by an infinitive.

So the structure is:

• Si bene valere vis = If you want to be healthy
• aquam puram ... bibere debes = you ought to drink pure water ...

Vis is the 2nd person singular present indicative of velle, meaning to want.

So:

• volo = I want
• vis = you want
• vult = he/she/it wants

It is an irregular verb, so its forms do not look like a regular -re verb.

In this sentence, vis means you want.

Bene is an adverb meaning well. It modifies valere.

The verb valere can mean things like:

• to be strong
• to be well
• to be healthy

But bene valere is a very natural Latin expression for to be in good health or to be well.

So bene is not unnecessary; it strengthens and clarifies the idea.

Because aquam puram is the direct object of bibere (to drink), so it must be in the accusative case.

• nominative: aqua pura = pure water as subject
• accusative: aquam puram = pure water as object

Since bibere takes a direct object, Latin uses the accusative:

• aquam = water
• puram = pure

The adjective puram agrees with aquam in:

• gender: feminine
• number: singular
• case: accusative

Because the sentence is contrasting pure water with wine, not pure water with pure wine.

So Latin only adds puram to aquam, because that is the thing being specially described. Vinum by itself just means wine.

Also, vinum is already in the accusative singular here. As a neuter noun, its nominative and accusative singular look the same, so you do not see a change in form.

Potius quam means rather than.

Here it compares two things:

• aquam puram
• vinum

So:

• aquam puram potius quam vinum = pure water rather than wine

A helpful way to understand it is:

• potius = rather / preferably
• quam = than

Latin often uses potius quam where English says simply rather than.

Because Latin usually does not need an explicit subject pronoun.

The verb endings already tell you the subject:

• vis = you want
• debes = you ought

So Latin can leave out tu (you) unless it wants extra emphasis.

If Latin said tu vis or tu debes, that would sound more emphatic, like you want or you should.

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

English depends heavily on position:

• You drink water is different from Water drinks you.

Latin depends much more on case endings and verb forms, so it can move words around more freely for emphasis or style.

In this sentence:

• Si bene valere vis
• aquam puram potius quam vinum bibere debes

the meaning is clear because:

• aquam and vinum are objects
• bibere is the infinitive
• debes is the main verb of the second clause

You could also see something like debes bibere, and it would mean the same thing. The chosen order here is natural and emphasizes the contrasted drinks before the final debes.

This is a straightforward present condition with si + indicative.

• Si ... vis = If you want ...
• ... debes = you ought ...

There is nothing especially hypothetical or contrary-to-fact here. It is a simple real condition:

• If you want to be healthy, you should drink pure water rather than wine.

So both verbs are in the present indicative because the sentence expresses a general truth or practical advice.

Classical Latin does not have definite or indefinite articles like English the, a, or an.

So:

• aquam can mean water, the water, or some water, depending on context
• vinum can mean wine, the wine, or some wine

English has to choose an article, but Latin usually leaves that idea unstated unless the context makes it clear.

Debes literally comes from debere, which originally has the sense to owe, and from there to be obliged to.

Depending on context, it can mean:

• you must
• you should
• you ought to

In this sentence, the tone is advice, so should or ought to is the best fit.

So bibere debes is not just a bare future action; it expresses recommendation or obligation:

• you should drink
• you ought to drink

Because after debes, Latin normally uses the infinitive to express what a person ought to do.

So:

• debes bibere = you ought to drink

The present infinitive bibere does not mean specifically to be drinking here. It simply gives the action in a general way: to drink.

This is the standard construction after verbs like:

• possum = I can
• volo = I want
• debeo = I ought

No. In this sentence, quam is not introducing a full clause; it is part of the comparison potius quam.

So it is functioning like than in English:

• pure water rather than wine

There is no separate verb after quam. It is just comparing one noun phrase with another.