How did composers write so much music so quickly in the Baroque and Classical eras? Were they all supreme geniuses? Not exactly: even composers of average talent could write reams of music every month because they were thoroughly trained in a technique of keyboard harmony known as partimento. Through the "Rule of the Octave" and other typical progressions, partimento allows you to instantly harmonize bass notes with beautiful chords and elegant voice-leading. John Mortensen is at the forefront of the international revival of improvisation in historical styles, and he is a perfect guide to introduce this rewarding topic. This video introduces the fundamental ideas behind partimento and explains its relevance to today's musicians.

Partimento is a technique of keyboard harmony which allows you to instantly harmonize bass scales with beautiful chords and elegant voice-leading. Join improvisation expert John Mortensen as he walks you through the most common and useful partimento progressions, demonstrating how this technique demystifies masterworks like the aria from Bach's Goldberg Variations as well as other Baroque keyboard works. Learn about the Rule of the Octave and the "cascade" progression on your path toward playing seamless improvisations.

The first step to improvising using a partimento bass line is to recognize the possible harmonies signaled by the given scale degrees. Join concert pianist and historical improviser John Mortensen as he walks you through Giovanni Furno's Partimento No. 1 in G major to practice recognizing both standard harmonizations and exceptions based on the Rule of the Octave.

Now that you've understood the harmonies implied by a partimento bass line and realized them in generic block chords, you may now stylize it. There are countless 18th-century styles that are suitable candidates for Furno's Partimento No. 1, and John Mortensen introduces you to the process of stylization with one of the most familiar and accessible genres of the Baroque period – the figuration prelude.

Join John Mortensen as he introduces you to the art of diminution – a stylization device that involves decorating a chordal realization with rhythmic filigree. Mortensen demonstrates two types of diminution as useful tools for decorating your own improvisations of Furno's Partimento No. 1 – dotted-diminution and non-chord tones.

Join John Mortensen as he introduces you to the weird and wonderful world of the unmeasured fantasia – a stylization device and improvisatory genre that draws heavily on free arpeggiation. Mortensen demonstrates how to arpeggiate Furno's Partimento No. 1, and apply voicing and timing to create special effects.

John Mortensen walks through the realization of Furno's Partimento No. 1, followed by four stylizations: figuration prelude, dotted-diminution, non-chord tone diminution, and unmeasured fantasia.

Mortensen: Composition in G major, on Furno's Partimento No. 1

John Mortensen performs an original composition based on Furno's Partimento No. 1 to demonstrate a model partimento improvisation.

The first step to improvising using a partimento bass line is to recognize the possible harmonies signaled by the given scale degrees. Join concert pianist and historical improviser John Mortensen as he walks you through Giovanni Furno's Partimento No. 2 in B minor to practice recognizing both standard harmonizations and special "4-6 Exceptions" based on the Rule of the Octave.

The next step toward improvising on a partimento is to realize the harmonies implied by the given bass line. Join concert pianist and historical improviser John Mortensen as he walks you through Giovanni Furno's Partimento No. 2 in B minor to practice realizing chords above the bass, drawing on your knowledge of the Rule of the Octave.

Now that you've understood the harmonies implied by a partimento bass line and realized them in generic block chords, you may now stylize it. There are countless 18th-century styles that are suitable candidates for Furno's Partimento No. 2, and John Mortensen introduces you to the process of stylization with one of the most familiar and accessible genres of the Baroque period: the figuration prelude.

Join John Mortensen as he introduces you to the art of diminution – a stylization device that involves decorating your chordal realization with rhythmic filigree. Mortensen demonstrates two types of diminution as useful tools for decorating your own improvisations of Furno's Partimento No. 2: dotted diminution and non-chord tones.

Join John Mortensen as he introduces you to the weird and wonderful world of the free fantasia – a stylization device and improvisatory genre that can draws on the arpeggios of the unmeasured fantasia, as well as scales, trills, and suspensions over the bass. Mortensen demonstrates how to use these devices in Furno's Partimento No. 2, and how to apply voicing and timing to create special effects.

John Mortensen plays through one possible realization of Furno's Partimento No. 1 in correctly harmonized block chords, followed by four stylizations: figuration prelude, neighbor notes, ornaments, and free fantasia.