"Everything's good in America!" If you know how to s(w)ing that, you know that a hemiola is "me -ri - ca." Though I cannot back this up scientifically I would venture to guess that every music in every culture since the beginning of time fooled around with triple meters (3 to the bar) dividing and multiplying each beat by 2.
The underlying point of the minuet, this rhythmic double entendre, explains why Baroque, classical, and even some modern composers wrote so many of them.
The hidden hemiolas are those places outside of dance movements in which, for example, a chord sustained for three-beats is bound by a slur to a "resolution" chord lasting one beat. I have learned to accent not the resolution chord, usually the first beat of the second measure, but the hidden strong hemiola beat: i.e., the third beat of the three-beat chord, weakening the chord change over the barline.
There are many such instances in the Schubert Impromptus and Moments Musicaux, not to mention the sonatas. Also in Beethoven, Mozart....
