Learn Hardcore Indonesian: Buku harian itu saya simpan di tempat rahasia untuk melindungi isi pribadi saya. - I keep that diary in a secret place to protect my personal contents.

Buku harian itu saya simpan…
= That diary, I keep (it) in a secret place… (topic = diary)
Saya menyimpan buku harian itu…
= I keep that diary… (topic = I)

Both are grammatically correct. The original sentence highlights the diary more than the person doing the action.

What’s the difference between saya simpan and saya menyimpan?

Both mean “I keep” here, but:

saya menyimpan: uses the standard active verb with prefix meN- (menyimpan from simpan). Neutral, very common.
saya simpan: uses the base form simpan without meN-. This often happens when:
- the object is moved to the front (Buku harian itu saya simpan…), or
- in more written/formal or slightly literary styles.

You could also say:

Buku harian itu saya menyimpan di tempat rahasia → grammatical but less natural.
Saya menyimpan buku harian itu di tempat rahasia → very natural, neutral.

What exactly does itu mean in Buku harian itu? Is it “that” or “the”?

Itu is a demonstrative meaning “that”, but in practice it often works like “that / the”:

buku harian itu
can be “that diary” (specific, already known in the context)
or effectively “the diary” in English.

It always comes after the noun:
buku harian itu, rumah itu, orang itu, not itu buku harian in this kind of phrase.

Why is the verb simpan in the base form after saya? Isn’t the base form usually imperative, like “keep!”?

The base form simpan can be:

imperative: Simpan buku itu! = Keep that book!
or a neutral verb form in certain structures, especially when:
- the object is fronted: Buku harian itu saya simpan…
- after some auxiliary verbs (e.g. mau makan, bisa pergi)

Here, saya simpan is not an imperative; the subject saya makes it clearly a statement: “I keep (it).”

What does buku harian literally mean? Is it exactly “diary”?

Literally:

buku = book
harian = daily / of the day

So buku harian = “daily book” → which corresponds to a diary (a book you write in daily).

You may also see diari (from English diary), but buku harian is the more standard Indonesian term.

Why is it di tempat rahasia, not ke tempat rahasia?

di = in / at / on (location)
ke = to (movement toward a place)

The sentence focuses on where the diary is kept, not the movement:

di tempat rahasia = in a secret place (location)
ke tempat rahasia = to a secret place (direction)

If you said Saya membawa buku harian itu ke tempat rahasia, that would mean “I take that diary to a secret place.” Different nuance.

How does untuk melindungi work? Could you just say melindungi without untuk?

untuk = for / in order to
melindungi = to protect (active verb from lindung)

untuk melindungi = “in order to protect / to protect”, introducing a purpose clause.

Without untuk, it sounds incomplete or like a different structure. In this sentence you need:

…di tempat rahasia untuk melindungi isi pribadi saya.

If you drop untuk, it would sound like two separate actions stuck together and is not natural here.

What does melindungi mean exactly, and how is it formed?

Root: lindung = protection, shelter
Prefix meN-
- lindung → melindungi = to protect, to guard, to shield

So melindungi isi pribadi saya = to protect my personal/private contents.

What exactly does isi pribadi saya mean? Why use isi and pribadi here?

Literally:

isi = contents / what’s inside something
pribadi = personal / private (related to the person)
saya = my

isi pribadi saya = my personal/private contents (what is written inside the diary, which is personal/private to me).

If you say:

privasi saya = my privacy (more abstract, personal sphere)
isi pribadi saya = the actual content that is personal

For a diary, isi pribadi saya is very natural because you’re protecting what’s written inside.

Why is the word order isi pribadi saya instead of isi saya pribadi?

Typical Indonesian noun phrase order is:

head noun → isi (contents)
adjective / descriptive word → pribadi (personal)
possessor → saya (my)

So: isi pribadi saya = my personal contents.

You can say isi saya (my contents), and saya pribadi (I personally / my own person), but isi saya pribadi would be unusual in this context and can sound awkward. Isi pribadi saya is the natural order.

Why is saya used twice? Can you drop the second saya?

First saya = subject of the verb simpan: I keep
Second saya = possessor of the contents: my (personal contents)

If you say:

Buku harian itu saya simpan di tempat rahasia untuk melindungi isi pribadi.

This would mean “to protect private contents” in general, not clearly my private contents. It’s grammatical but less specific.

Keeping saya twice is natural and clear:
I keep that diary in a secret place to protect my private contents.

Is this sentence formal, informal, or neutral? How would a more casual version look?

The sentence is neutral to slightly formal, especially because of the object-fronting Buku harian itu saya simpan….

More casual versions could be:

Aku simpan buku harian itu di tempat rahasia supaya nggak ada yang tahu isinya.
(uses aku, nggak, and supaya; more colloquial)

A neutral but very common word order:

Saya menyimpan buku harian itu di tempat rahasia untuk melindungi isi pribadi saya.

Can I instead say Saya menyimpan buku harian itu di tempat rahasia untuk melindungi isi pribadi saya? Does it change the meaning?

Yes, that sentence is completely correct and very natural.

The difference:

Buku harian itu saya simpan… → emphasizes the diary (topic/fronting)
Saya menyimpan buku harian itu… → more neutral, subject-first word order

The meaning is the same: you keep that diary in a secret place to protect your private contents. The change is mainly in focus and style, not in basic meaning.