Example of dissonance in Bach's Well-Tempered Clavier, Vol. I (Preludio XXI). The chord in question was pointed out in: Marquis, G. Welton (1964). Twentieth Century Music Idioms. Englewood Cliffs, New Jersey: Prentice-Hall, Inc. Presumably Marquis is the source of the tempo, dynamic, and, in the second measure, arpeggiation.
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