Ego suspicor canem micam e mensa cepisse; mater autem dicit nihil certum esse.

Yes — Latin could simply say suspicor.

The ending -or already tells you the subject is I, so ego is not grammatically necessary. When Latin includes ego, it usually adds emphasis or contrast.

So Ego suspicor ... ; mater autem dicit ... suggests something like:

• I suspect ...
• but mother says ...

That makes the contrast between the two speakers clearer.

Because suspicor is a deponent verb.

Deponent verbs:

• have passive-looking forms
• but active meanings

So:

• suspicor = I suspect
• not I am suspected

This is a very common feature in Latin, and learners often need time to get used to it.

In English, yes: the dog is the subject of took.

But after verbs like suspicor and dicit, Latin often uses an indirect statement construction called the accusative-and-infinitive.

So instead of saying something like:

• I suspect that the dog took...

Latin says, more literally:

• I suspect the dog to have taken...

That is why:

• canem is accusative: it is the subject of the infinitive cepisse
• micam is also accusative, but for a different reason: it is the direct object of cepisse

So in canem micam e mensa cepisse:

• canem = the dog, subject of the infinitive
• micam = the crumb, object of the action

Because Latin is using indirect statement after suspicor.

After verbs of:

• saying
• thinking
• knowing
• believing
• suspecting

Latin very often uses:

• accusative subject + infinitive

So:

• canem ... cepisse = that the dog took / has taken / had taken

If Latin used cepit, it would no longer be the normal indirect-statement construction.

Cepisse is the perfect active infinitive of capio.

In indirect statement, the tense of the infinitive is usually understood relative to the main verb, not as an absolute tense in the same way as English finite verbs.

So cepisse shows action earlier than suspicor:

• I suspect that the dog took the crumb
• I suspect that the dog has taken the crumb
• sometimes even had taken, depending on context

The main point is that the taking happened before the suspecting.

E (or ex) means out of or from, and it takes the ablative.

So:

• mensa here is ablative singular
• e mensa = from the table

This is a standard prepositional phrase:

• e/ex + ablative

Latin uses e before many consonants and ex before vowels or sometimes for sound preference, but both mean the same thing.

Autem means however, but, or on the other hand.

A very important point: autem is usually postpositive, which means it tends to come second in its clause, not first.

So Latin says:

• mater autem dicit

not usually:

• autem mater dicit

This is normal Latin word order for autem.

It gives a mild contrast:

• I suspect...
• mother, however, says...

It is often a bit softer than a strong but.

It is another indirect statement.

Main verb:

• dicit = says

Indirect statement:

• nihil certum esse = that nothing is certain

More literally, Latin is saying:

• mother says nothing to be certain

In this construction:

• nihil is the subject of the infinitive esse
• certum is a predicate adjective agreeing with nihil
• esse is the infinitive to be

So the whole phrase means:

• that nothing is certain

Because it agrees with nihil.

Nihil means nothing, and it is grammatically neuter singular in sense. Therefore the adjective that goes with it is also neuter singular:

• nihil certum = nothing certain

Then in indirect statement:

• nihil certum esse = that nothing is certain

So certum is not random — it matches nihil.

Here it functions as the accusative subject of the infinitive esse, because it is inside an indirect statement after dicit.

However, nihil is one of those words whose form does not clearly change the way many ordinary nouns do. In practice, learners often just recognize it by its role in the sentence.

So syntactically here:

• mater dicit [nihil certum esse]
• nihil = subject of esse inside the accusative-and-infinitive construction

That is why English translates it as the subject of the clause:

• Mother says that nothing is certain

Latin normally must include esse in this kind of indirect statement.

So:

• nihil certum esse literally = nothing to be certain
• idiomatically = that nothing is certain

English can sometimes feel less explicit, but Latin regularly uses the infinitive esse when forming this structure.

The grammar does not depend mainly on word order, because the endings show the relationships. But the order still helps with emphasis and flow.

For example:

• Ego suspicor puts some emphasis on I
• mater autem highlights the contrast with mother
• canem micam e mensa cepisse keeps the indirect statement together as a unit

A native English speaker may want to rearrange it into a more English-like order, but Latin often prefers to group ideas by structure and emphasis rather than by a fixed subject-verb-object pattern.