I think this may be a good way to remember this: ähnlich is 'similar', and when used in a sentence like the one above, it is 'similar to'. (Actually i think the word 'zu' or 'mit' or something is missing here, although i'm not sure which word, if any, is missing.) So the other part automatically goes to dative.
Thank you! That makes so much sense. "Du bist eine Maus ähnlich" would basically mean "You are a mouse similar." But "Du bist einer Maus ähnlich" means "You are to a mouse similar."
I guess it helps to think "ähnlich" literally just means "similar," not "similar TO." In order to add the "to" in there, you have to have something in the dative, which goes along with what someone said above where her dictionary said "similar to" = aenlich + dative.
Flowers for Algernon: June 23—I’ve given up using the typewriter completely. My co-ordination is bad. I feel that I’m moving slower and slower. Had a terrible shock today. I picked up a copy of an article I used in my research, Krueger’s Uber psychische Ganzheit, to see if it would help me understand what I had done. First I thought there was something wrong with my eyes. Then I realized I could no longer read German. I tested myself in other languages. All gone. This is nightmare
The article "einer" is in dative form because "maus" is a die word, and whenever you put an adjective and a dative form together, whether it's an article or a personal pronoun like "mir", the adjective comes last. This is one of the things to keep in mind about the structural differences between English and German, so for example saying "important to me" would be "mir wichtig" in German, not "wichtig mir" like it would be with English sentence structure. However, it would also be correct to translate it as "wichtig für mich", in which case the adjective wouldn't come last since dative case isn't used.
There's an extra article. If you meant "alike" then that would not be correct either, because like I've pointed out to someone else here, "alike" requires at least two subjects, so you could say "you and the mouse are alike", but saying "you are alike a mouse" isn't proper English.