The Instrumental of Route and Time | Czech Grammar

You already know the instrumental as the case of means — autem (by car), perem (with a pen). This page covers a quieter, more advanced relative of that use: the instrumental of route, the path along or through which motion happens, and a small set of frozen time expressions that survive as bare instrumentals. Both are places where English reaches for a preposition — through, along, via — and Czech reaches for nothing but the case ending. They answer the question kudy? ("which way? by what route?"), the route-cousin of kde? and kam?.

Route: the path you move along

When motion runs along or through a stretch of space, Czech can put that space straight into the bare instrumental — no preposition at all. This is the same logic as means: the road, the forest, the door is the "channel" by which the motion is accomplished, so it behaves like an instrument. English needs through the forest, along the motorway, through the door; Czech needs only lesem, dálnicí, dveřmi.

Šli jsme lesem až k řece.

We walked through the forest all the way to the river. (lesem — bare instrumental of les, the route)

Do Brna pojedeme dálnicí, je to rychlejší.

We'll go to Brno along the motorway, it's faster. (dálnicí — instrumental of dálnice, the path taken)

Vešel dveřmi a sedl si k oknu.

He came in through the door and sat down by the window. (dveřmi — instrumental plural of dveře, 'through the door')

Notice that the case answers a different question from the destination. Kam jdeš? ("Where to?") is answered with do lesa (genitive — into the forest, a goal). Kudy jdeš? ("Which way?") is answered with lesem (instrumental — through the forest, the route). The two coexist in one sentence without clashing:

Domů to vezmu parkem, je to kratší cesta.

I'll take the route home through the park, it's a shorter way. (parkem — the route; the verbless 'vzít to' = 'take that way')

Jeli jsme tam lesní cestou a zpátky po silnici.

We went there along the forest track and back along the road. (lesní cestou — bare instrumental route; po silnici contrasts the 'po + locative' alternative)

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The route instrumental answers kudy? — "which way?" If you can paraphrase the English with through, along, or via and the noun is the channel of movement, the bare instrumental is your form: lesem, dálnicí, oknem, chodbou, mostem.

Why not přes or skrz?

This is the single most useful thing on the page. English speakers, hunting for the word through, grab přes or skrz — both of which exist and both of which take the accusative. But they do not mean a route you travel inside. Přes + accusative means across / over a surface or a barrier (přes most = across the bridge, přes ulici = across the street); skrz + accusative means through in the sense of piercing something (skrz zeď = through the wall, by passing through its substance). Neither one renders "moving along the inside of a space." For that, Czech wants the bare instrumental.

Prošli jsme lesem na druhou stranu.

We walked through the forest to the other side. (lesem — moving along inside it; přes les would wrongly suggest crossing over its top)

Přešli jsme přes most a pak dál parkem.

We crossed over the bridge and then on through the park. (přes most acc — across a barrier; parkem instr — the route through)

Kulka prolétla skrz dveře.

The bullet flew through the door. (skrz + accusative — piercing the material; this is NOT a route you travel)

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Three "throughs," three jobs: lesem (instrumental) = moving along inside a space; přes + acc = across a surface or barrier; skrz + acc = piercing the substance of something. Reaching for přes/skrz when you mean "along the inside" is the classic English-speaker slip.

The literary flavour of route instrumentals

Be honest with yourself about register here. Jet dálnicí, jít lesem, projít chodbou, vejít dveřmi are perfectly ordinary and you will hear them daily. But once the route gets longer or more abstract, the bare instrumental tilts (literary) and a prepositional paraphrase with po + locative is the everyday choice. Šel ulicí is fine but slightly elevated; šel po ulici is the neutral spoken version. The longer and more "journey-like" the path, the more a careful writer leans on the bare instrumental for its compactness and a speaker leans on po.

Kráčel liduprázdnou ulicí a poslouchal ozvěnu vlastních kroků.

He strode along the deserted street, listening to the echo of his own footsteps. (ulicí — bare instrumental, distinctly literary in tone)

Šel jsem po ulici a potkal jsem Honzu.

I was walking down the street and I ran into Honza. (po ulici — the neutral, everyday way to say the same route)

Manner of motion: instrumental of speed and means again

Closely tied to route is manner, especially speed, which the instrumental also handles bare. Rychlostí sto kilometrů za hodinu ("at a speed of 100 km/h") is an instrumental of means: the speed is the "means" by which the motion proceeds. This shades back into the ordinary instrumental of means, but it's worth flagging that motion verbs collect these instrumentals naturally.

Vlak projížděl stanicí rychlostí sto třicet kilometrů za hodinu.

The train passed through the station at a speed of 130 km/h. (stanicí — route; rychlostí — manner/speed, both instrumental)

Auto se řítilo plnou rychlostí po dálnici.

The car was racing at full speed along the motorway. (plnou rychlostí — manner, bare instrumental)

Time: the frozen instrumentals that survived

Old Czech once used the instrumental freely for "time during which," and most of those forms have since hardened into adverbs or been replaced by prepositional phrases. The everyday words for parts of the day are now plain adverbs — ráno (in the morning), večer (in the evening), odpoledne (in the afternoon) — and you should not try to manufacture *večerem as a living time form. What survives are a handful of fixed, idiomatic instrumentals that every speaker uses without thinking of them as a "case" at all:

Form	Meaning	From
časem	in time, eventually, with time	čas (time)
cestou	on the way, en route	cesta (way, journey)
chvílemi	now and then, at moments	chvíle (moment)
dnem i nocí	day and night, round the clock	den, noc
léty / lety	over the years	léta / roky (years)

These are best learned as vocabulary, not generated from a rule. Časem is the most useful: it means "eventually / in due course," carrying the idea that time itself is the means by which something comes about.

Neboj, časem si na to zvykneš.

Don't worry, you'll get used to it in time. (časem — bare instrumental, 'eventually / with time')

Cestou domů jsem se zastavil v lékárně.

On the way home I stopped at the pharmacy. (cestou — frozen instrumental, 'en route'; it also keeps its route meaning here)

Chvílemi svítilo slunce, chvílemi pršelo.

Now and then the sun came out, now and then it rained. (chvílemi — instrumental plural, 'at moments / on and off')

Pracovali dnem i nocí, aby to stihli.

They worked day and night to get it done in time. (dnem i nocí — a fixed instrumental pair, 'round the clock')

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Don't try to put parts of the day into the instrumental — say ráno, večer, odpoledne (plain adverbs). The instrumental survives only in fixed phrases: časem (eventually), cestou (on the way), chvílemi (on and off). Treat these as set vocabulary.

Common Mistakes

The errors cluster around importing an English preposition where Czech wants a bare ending — or inventing a time-instrumental that doesn't exist.

❌ Šli jsme přes les k řece.

Incorrect for 'along/through the forest' — přes les means crossing over it; the route inside takes the bare instrumental.

✅ Šli jsme lesem k řece.

We walked through the forest to the river.

❌ Vešel skrz dveře.

Incorrect — skrz means piercing the material; entering by way of the door is the bare instrumental.

✅ Vešel dveřmi.

He came in through the door.

❌ Pojedeme po dálnicí.

Incorrect mix — either bare instrumental dálnicí, or po + locative po dálnici (po never takes the instrumental).

✅ Pojedeme dálnicí.

We'll go along the motorway.

❌ Večerem půjdeme do kina.

Incorrect — 'in the evening' is the plain adverb večer; večerem is not a living time form.

✅ Večer půjdeme do kina.

In the evening we'll go to the cinema.

❌ S časem si zvykneš.

Incorrect — 'in time / eventually' is the bare instrumental časem, with no preposition s.

✅ Časem si zvykneš.

You'll get used to it in time.

Key Takeaways

The route instrumental answers kudy? and marks the path moved along or through: lesem, dálnicí, dveřmi, parkem — no preposition.
It is not přes (across a barrier) or skrz (piercing the substance); reaching for those is the main English-speaker error.
Longer/abstract routes tilt (literary); the everyday spoken alternative is po
- locative (po ulici, po silnici).
For time, parts of the day are plain adverbs (ráno, večer); the instrumental survives only in frozen phrases — časem (eventually), cestou (on the way), chvílemi (on and off).

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