Dies ist eine Katze or diese ist eine Katze?
Why is the demonstrative pronoun "dies" not written in the form "diese" if it refers to a feminine noun? Would it be viewed as incorrect to use diese?
Dies is short for dieses. Dies/dieses is singular nominative neuter and doesn't refer to the cat directly. Thus it doesn't match case, gender and number of the singular feminine nominative noun Katze. Like in other German idioms such as es ist (~it is) or es gibt (~there is), the neuter pronoun is referring to a yet unspecified object, concept or notion. I recommend learning this as an idiom.
It's kind like saying it is a girl in English, if you don't know the gender or if you have just discovered that the baby is a she. Another way of thinking of this is, that the it refers to a neuter noun that was mentioned earlier (like the baby or in case of the German idiom the neuter noun das Tier).
Diese ist eine Katze ist not a common way of saying that. It's correct grammar though. Here, the demonstrative pronoun refers to cat. It puts a strong emphasis on the cat. It translates to something like (Look! Over there!) This (one) is a cat. (While all other animals we spotted so far were other species)
It's like in Spanish.
estO es un gato
estO es una gata
Also possible to say "estA... es una gata" or "estE.... es un gato"
but it means, then, "This one (!)... is a cat"
Not native, but gaining experience ;)
The way I see it, "dies" is a somewhat emphasized "that" (stronger than a simple "Das ist eine Katze", that you could translate as "This is a cat").
"Diese ist eine Katze" would be "This one is a cat (and what is the other animal?)", so "diese" is a pronoun, that you of course declinate ("Dieses ist ein Pferd"; "Dieser ist ein Hund").
Hope it helps :)
Yes, diese is feminin. But as well it means "a specific": "Viele Katzen sind schwarz, doch DIESE hat einen weißen Fleck auf der Brust."
or: DER Hund
"Viele Hunde sind braun, doch DIESER hat einen hellen Fleck auf dem Rücken."