Magister dicit: “Si veritatem dicitis, gaudium vincet; si mendacium dicitis, timor latet in mente.”

Because magister is the subject of dicit (The teacher says). The nominative is used for the subject of a finite verb.

• dicit = he/she says (3rd person singular), referring to magister.
• dicitis = you (plural) say / you (all) speak (2nd person plural), addressing the people being spoken to inside the quotation.

If the teacher were addressing one person, it would be dicis.

Latin commonly expresses tell the truth / speak the truth as veritatem dicere (literally, to say the truth), where:

• veritatem is the direct object in the accusative
• dicitis is the verb

English uses “tell” + object more often, but Latin often uses dicere this way.

veritas is nominative (truth as a subject).
veritatem is accusative (truth as a direct object).

Here it’s the thing being said: you speak the truth, so it must be accusative.

It’s 3rd declension, feminine:

• nominative: veritas
• accusative: veritatem

A common clue is the accusative singular ending -em (though not all 3rd declension nouns use it in every pattern).

Because mendacium is a 2nd declension neuter noun. In neuter nouns:

• nominative singular = accusative singular

So mendacium can mean a lie as either subject or direct object; here it’s a direct object of dicitis.

They describe consequences in slightly different ways:

• gaudium vincet = joy will win/prevail (future result)
• timor latet in mente = fear lies hidden in the mind (present-state consequence, stated as a general reality)

You could make them match more tightly (e.g., timeor latebit), but Latin doesn’t have to keep both apodoses in the same tense if the sense differs.

Both are 3rd person singular:

• vincet = he/she/it will conquer (from vinco)
• latet = he/she/it lies hidden (from lateo)

They match their subjects:

• gaudium (singular) → vincet
• timor (singular) → latet

With in:

• in + ablative = location (in the mind, where something is)
• in + accusative = motion toward (into the mind, where something goes)

Since fear is described as already being there/hidden there, Latin uses in mente (ablative).

Yes—Latin word order is flexible, and putting the object first can add emphasis or clarity:

• veritatem dicitis highlights truth as the key choice
• mendacium dicitis highlights lie as the alternative

It also creates a neat parallel structure between the two conditional clauses.

Because this is a straightforward conditional, treating the condition as a real possibility:

• si dicitis ... vincet / latet

Latin tends to use the subjunctive in more “remote” or contrary-to-fact conditionals (e.g., si diceretis..., si dixissetis...) or in certain subordinate nuances. Here the speaker is presenting a direct choice with direct outcomes, so the indicative is natural.

It sets up two parallel alternatives:

• If you speak the truth...
• If you speak a lie...

Latin often uses repeated si clauses like this for balance and contrast, especially in moral or rhetorical statements.