Haydn’s Piano Sonata in Bb Minor Joseph Haydn was one of the most prominent and prolific composers of the Classical period, often called the “Father of the Symphony” and the “Father of the String Quartet.” While I can personally attest to the brilliance of both his string quartets and symphonies, today I will instead be focusing on one of his piano sonatas and examining its form and chord structure. The Exposition of the sonata begins in measure one and ends in measure sixty-one at the cadence of the closing theme. Inside this exposition lie multiple themes, the first theme stretching from measure one to measure twenty-two, where the second theme group begins. The first theme has three phrases in it: measures one through ten, eleven through fifteen, and sixteen through twenty-one, all of which stay in the key of B flat major. Though they are all in the same key, the phrases make up a contrasting period because measures one through ten are obviously different than the two following phrases, which are similar. Moving on to the second theme which is the key of F major, the dominant, we can see that the phrases are contrasting as well because they do not begin similarly and have different chord structure. An interesting composition technique is extending phrases through various means such as sequences or repetition, both used by Haydn in the exposition. Measures seven through ten, twenty-nine through thirty, forty-one through forty-two and forty-eight through fifty-five are all examples of repetition. We can see sequences in measures seventeen through twenty and twenty-two through twenty-seven. Lastly in measures fifty-six though sixty-one Haydn uses a cadential extension to lengthen the closing phrase. To focus more on chord structure we will focus on Haydn’s use of augmented sixth chords and secondary dominants to enrich the exposition. Measures eleven and sixteen both contain the secondary dominant of the subdominant chord and measures twenty-seven and twenty-nine both contain a German augmented sixth chord that resolves to the dominant, C. Closing out our study on the exposition in measure forty-eight is the closing theme, a phrase that is lengthened an extra five measures in measures fifty six through sixty one with a cadential extension. The Development is the second section of a Sonata, a section typically rampant with sequences to move through keys from which Haydn’s sonata is no exception. The development starts with a basic theme that is varied upon throughout the section, a theme that is seen from measures sixty-two to seventy. The only actual sustained key in the development is F major, though a listener might be fooled by the dominant sequences and quickly moving chords. There are five sequences throughout the development: a modulating sequence from seventy-one to seventy-six, a descending fifths sequences from seventy-seven to eighty-three, an ascending fifths sequence from eighty-four to eighty-eight, a secondary dominant sequence descending by seconds from ninety-one to ninety-five, and an ascending five-six sequence from ninety-nine. These sequences make up the body of the development which leads into the Recapitulation. The Recapitulation starts in measure 102 and stretches to the end, sustaining the key of the tonic the whole way there, B flat major. The recapitulation retains the exposition almost identically but measure 108 is not present in the original and functions as a replacement for measures ten through twenty-two. This transition into the next phrase eliminates the modulation into the dominant that is present in the exposition, explanation for the extensive phrase in only B flat major. Through these analyses it is obvious that though Haydn was the original father of string quartets and symphonies, piano sonatas were a well-developed child of his as well.