While you clothing was all black you still had to have them cut in different styles. You needed morning dress and afternoon dress, tea dress, calling dress, dinner dress, evening dress (after the first six months you were allowed small quiet entertainments) riding dress, traveling dress. You needed several of each because it just would Not Do to be caught wearing the same dress in close sequence.
Let's not even talk about half morning and quarter morning.
or you were NORMAL and owned 1 house dress and 1 church dress.