Avia puero flenti dicit cor eius bonum esse et lacrimas eius tergit.

Because it is the indirect object of dicit.

• dicit = she says
• She says something to the boy
• In Latin, the person to whom something is said is usually put in the dative

So:

• puero = to the boy
• flenti = crying, agreeing with puero

Together, puero flenti means to the crying boy.

Because flenti has to agree with puero.

The participle flens means crying, but its form changes depending on case, number, and gender, just like an adjective.

Since puero is:

• dative
• singular
• masculine

the participle must also be:

• dative
• singular
• masculine

So:

• nominative: flens
• accusative: flentem
• dative: flenti

That is why Latin uses puero flenti.

Flenti is a present active participle from flere, meaning to weep or to cry.

A present participle usually describes someone as doing something at that moment or in an ongoing way.

So puero flenti literally means to the boy crying or more naturally to the crying boy.

This is a very common Latin construction called an indirect statement.

Instead of saying:

• She says that his heart is good

Latin often says:

• She says his heart to be good

That sounds strange in English, but it is normal in Latin.

Here:

• dicit = she says
• cor eius bonum esse = that his heart is good

The infinitive esse is the standard way Latin builds this kind of reported statement after verbs like:

• dicit = says
• putat = thinks
• scit = knows
• audit = hears

Because esse is the infinitive in the indirect statement: cor eius bonum esse.

Latin often puts the infinitive at the end of that clause, especially with forms of to be, though word order in Latin is flexible.

So the structure is:

• cor = heart
• eius = his
• bonum = good
• esse = to be

Together: that his heart is good.

Because bonum agrees with cor, and cor is neuter.

• cor = heart
• It is a neuter noun
• Therefore the adjective describing it must also be neuter singular nominative

So:

• masculine: bonus
• feminine: bona
• neuter: bonum

That is why Latin says cor bonum, not cor bonus.

Cor is nominative singular.

In the indirect statement cor eius bonum esse, cor is the subject of the infinitive esse.

So even though the whole clause depends on dicit, inside that clause:

• cor is the thing being described
• bonum describes cor
• esse links them

So cor stays nominative because it is the subject of esse.

This is a very common question.

Latin uses:

• suus, sua, suum for a reflexive possessive, referring back to the subject
• eius for his / her / its, referring to someone else

In this sentence, the main subject is avia:

• Avia ... dicit ... tergit
• The grandmother says ... and wipes ...

So if Latin used suum, it would normally mean the grandmother's own heart or tears.

But the sentence means the boy's heart and tears, not the grandmother's. Since the boy is not the grammatical subject of the main verb, Latin uses eius.

So:

• cor eius = his heart
• lacrimas eius = his tears

By itself, eius can mean:

• his
• her
• its

The form is the same for all three in the singular genitive.

You figure out which one is meant from the context. Here, because the sentence includes puero flenti (to the crying boy), eius is naturally understood as his.

Because lacrimas is the direct object of tergit.

• tergit = she wipes
• What does she wipe? the tears

So lacrimas must be in the accusative plural.

Its dictionary form is lacrima, and here we have:

• nominative singular: lacrima
• accusative singular: lacrimam
• accusative plural: lacrimas

Latin often just uses et to join two verbs, and the sequence is understood from context.

So:

• dicit = she says
• et ... tergit = and wipes

English might translate this as:

• The grandmother speaks to the crying boy and wipes his tears
• or The grandmother tells the crying boy that his heart is good and wipes his tears

Latin does not need to add a special word for then unless the writer wants to emphasize sequence.

Latin word order is much freer than English word order because the endings show each word's job in the sentence.

This sentence is arranged quite naturally in Latin:

• Avia = subject first
• puero flenti = the person spoken to
• dicit = main verb
• cor eius bonum esse = what she says
• et lacrimas eius tergit = second action

English depends heavily on position, but Latin depends much more on case endings and verb forms. So Latin can move words around for emphasis or style without making the sentence unclear.

A simple way to divide it is:

1. Avia puero flenti dicit

   • The grandmother says to the crying boy

2. cor eius bonum esse

   • that his heart is good

3. et lacrimas eius tergit

   • and she wipes his tears

So the overall structure is:

• main clause
• indirect statement
• second coordinated verb

Because its subject is avia, which is singular.

• avia = grandmother
• tergit = she wipes

The same subject also goes with dicit:

• avia ... dicit
• avia ... tergit

Latin often does not repeat the subject if it stays the same.

Yes. A very literal translation would be:

• that his heart to be good

But that is not natural English. The normal English translation is:

• that his heart is good

This is one of those places where a literal translation helps you see the Latin structure, but a smoother translation gives the real meaning in English.