Dative pronoun when translating repeating personal pronoun sentence in English [duplicate]

Question

I was always cold, I didn't swim in the lake often.

Translation (acc. duolingo): Mir war immer kalt, Ich bin nicht oft im See geschwommen.

Doubt: Why does first clause start with mir rather than ich?

What I know: Mir is a dative pronoun, so something related to dative case is going on here?

Answer 1

This use of mir is common in German and the source of a lot of confusion for learners, so I'd be surprised if this hasn't already been covered here several times. (In fact I asked a related question a long time ago.) There are three things going on which should explain it all:

1. The subject es has been dropped. This is the "impersonal es" often used when talking about the weather: Es regnet -- It's raining, Es ist kalt -- It's cold. The corresponding English word "it" is mandatory, but the German es is sometimes optional, especially in spoken German when the meaning is clear without it. For a learner, mentally fill in the missing es so that the sentence has a subject: Es war mir immer kalt.
2. The dative here is something I call the point-of-view dative. It says that the statement is true according to someone's point of view. Without mir, Es war immer kalt says it was always cold, a plain fact and not a matter of opinion or perspective. Es war mir immer kalt literally says "It was, from my point of view, cold." In other words you felt cold. English uses the same phrase for two different meanings, "I am cold" can mean either that you feel cold (uncomfortable because of the temperature) or that you actually are cold (your body temperature is below normal). German uses different phrases for the different meanings.
3. Remember that word order in German is different than English. You can drop the subject es, but something still has to appear in front of the verb, so the mir is moved to the front. In this case, mir is not the subject, for one thing it's in the wrong case. It can be confusing for English speakers who are used to always seeing the subject before the verb, but in German, any sentence element can be first, as long the verb somes second. The upshot is that sentences like Mir ist kalt, Uns ist heiß, are perfectly grammatical and make sense once you understand the differences between German grammar and English grammar.

The most difficult aspect of this construction is figuring out which adjectives it's applied to. The adjective kalt is an environmental adjective; it describes the general atmosphere. But müde describes a person, so you'd say Ich bin müde. But the difference between "environmental" and "personal" adjectives can seem rather random to English speakers, for example: Mir ist langweilig -- "I'm bored" (Literally, "To me it's boring".) It's best to keep an eye out for these "environmental" adjectives as you learn them, and in general always try to find out how a word is used in a sentence instead of just equating it to a word in English.

Answer 2

In addition to RDBury's comprehensive answer, it's probably helpful to think of it as an "implied passive", so to speak. You could say, "who's doing the cold to whom" ;)

In

Das Glas ist kalt.
The glass is cold.

the glass "is doing the cold" and can, for example, chill the drink in it. On the other hand, in

Mir ist kalt.
I'm cold.

I'm getting chilled by my cold environment. My environment is "doing the cold", I'm the recipient of the coldness, so to speak.

We're not talking about passive voice grammatically / technically, mind you, but more about an implication on the meaning level. And the idea of something "doing its cold to something else" will probably make everybody who remembers some middle school physics raise an eyebrow, but that's the way the phrasing works ;)

The basic idea is also used for other points on the temperature spectrum, like "Mir ist warm" or "Mir ist heiß", but also in phrase like "Mir ist langweilig" (something is boring me, something is doing the boredom to me). Occasionally, the "actor" is still present in the sentence, for example in "Das ist mir peinlich" (this is embarassing to me).