Learn Hardcore French: Le médecin veut guérir Marie rapidement.

Le médecin means the doctor (a specific doctor already known in the context).
Un médecin would mean a doctor (any doctor, not specified).

So the choice of le vs un depends on whether the speaker has a particular doctor in mind.

Is médecin masculine or feminine? How do you talk about a female doctor?

Grammatically, médecin is masculine, even when referring to a woman.

Le médecin can refer to a male or a female doctor.
In real life, people may say une femme médecin to insist on the fact that the doctor is a woman, but the noun médecin itself stays masculine.

Example:

Le médecin est très compétent. Elle travaille à l’hôpital.
(The doctor is very competent. She works at the hospital.)

Why is it veut guérir and not something like veut de guérir or veut à guérir?

In French, some verbs can be followed directly by an infinitive without a preposition. Vouloir is one of them.

Pattern:

vouloir + infinitive

Examples:

Je veux manger. – I want to eat.
Nous voulons partir. – We want to leave.
Le médecin veut guérir Marie. – The doctor wants to cure Marie.

So adding de or à (veut de guérir, veut à guérir) is incorrect here.

Why veut and not something like veux or vouloir?

Veut is the 3rd person singular (il/elle/on) form of vouloir in the present tense:

je veux
tu veux
il / elle / on veut
nous voulons
vous voulez
ils / elles veulent

Since the subject is Le médecin (he/she), we use il/elle veut → Le médecin veut.

What exactly does guérir mean? Is it the same as soigner or traiter?

Guérir means to cure, to heal – to make someone healthy again, to eliminate the disease.

guérir quelqu’un – to cure someone
guérir d’une maladie – to recover from an illness

By contrast:

soigner = to treat, to care for (you look after the patient, give treatment, but it doesn’t automatically mean you cure them).
traiter = to treat medically (more technical/medical; about the treatment, not necessarily the final result).

So:

Le médecin veut guérir Marie. – He wants her to be cured, to be healthy again.
Le médecin soigne Marie. – He is treating/caring for Marie.

Why is there no preposition before Marie after guérir?

Guérir takes a direct object when you say who is being cured:

guérir quelqu’un – to cure someone

So you say:

guérir Marie
guérir le patient
guérir les enfants

No à, de, or other preposition is used before the person’s name in this structure.

Could the word order be Le médecin veut guérir rapidement Marie instead?

The standard and most natural order is:

guérir Marie rapidement (verb + object + adverb)

Putting rapidement right before Marie (guérir rapidement Marie) sounds odd and unnatural in this sentence.

In French, adverbs like rapidement most often go:

after the infinitive alone: veut rapidement guérir Marie (possible, but a bit more literary or emphatic)
or after the verb + object: veut guérir Marie rapidement (most natural here)

So the given sentence uses the most usual, neutral word order.

What’s the difference between rapidement and vite? Could I say … guérir Marie vite?

Both rapidement and vite can mean quickly, but:

rapidement is more neutral/formal.
vite is more colloquial and a bit more common in speech.

You can say:

Le médecin veut guérir Marie rapidement.
Le médecin veut guérir Marie vite.

Both are correct. Vite is just a bit more casual.

How would I replace Marie with a pronoun?

Marie is a direct object (who is being cured), so you use the direct object pronoun la.

With an infinitive, the pronoun goes before the infinitive:

Le médecin veut la guérir rapidement. – The doctor wants to cure her quickly.

Placement pattern here:
subject + conjugated verb + object pronoun + infinitive + rest

Example:

Je vais le voir demain. – I’m going to see him/it tomorrow.
Le médecin veut la guérir rapidement.

If I change the tense to the past, how do I say The doctor wanted to cure Marie quickly?

Two common options, depending on context:

Imparfait (background, ongoing state in the past)
- Le médecin voulait guérir Marie rapidement.
  → He wanted to cure her (general/ongoing desire in the past).
Passé composé (completed action, one-time event)
- Le médecin a voulu guérir Marie rapidement.
  → He tried / decided to cure her quickly at a particular moment.

Both are grammatically correct; the nuance depends on the story you’re telling.

Does rapidement change form to agree with Marie or médecin?

No. Rapidement is an adverb, and adverbs in French are invariable: they never change form for gender or number.

Marie court rapidement.
Les enfants courent rapidement.

The word rapidement stays exactly the same in all cases.

How would I make this sentence negative?

Use ne … pas around the conjugated verb (veut), not around guérir:

Le médecin ne veut pas guérir Marie rapidement.
→ The doctor does not want to cure Marie quickly.

Pattern:
subject + ne + conjugated verb + pas + infinitive + rest

Example:

Je ne veux pas partir. – I don’t want to leave.
Le médecin ne veut pas guérir Marie rapidement.

Why don’t we put an article before Marie (like la Marie)?

In standard French, you do not put an article before normal given names:

Marie, Paul, Sophie, Karim, etc. (no article)

So you say:

Le médecin veut guérir Marie.

Using la Marie, le Paul, etc. can occur in some dialects or for special stylistic effects (often familiar or slightly pejorative), but it is not the neutral, standard form.