Episode 1: 1920s

The 1920s marked a revolutionary period in music history. Jazz, born from the fusion of African American musical traditions and European classical harmony, introduced the world to entirely new ways of thinking about chord progressions. This era laid the foundation for virtually all modern popular music.

The 1920s were a time of unprecedented cultural exchange. In cities like New Orleans, Chicago, and New York, African American musicians combined traditional blues and spirituals with European classical harmony, creating something entirely new. This fusion gave birth to jazz and fundamentally changed how musicians approached chord progressions.

The ii-V-I progression became the cornerstone of jazz harmony during this period. This simple yet powerful progression (Dm7 - G7 - Cmaj7 in the key of C) provided a framework that would influence music for the next century.

This progression creates a strong sense of resolution and movement. The ii chord (Dm7) creates tension, the V chord (G7) intensifies it, and the I chord (Cmaj7) provides the satisfying resolution. This pattern became so fundamental that it's still the most common progression in jazz today.

The ii-V-I progression works because it follows the natural harmonic tendencies of Western music. The ii chord contains the 4th scale degree, which naturally wants to resolve down to the 3rd. The V chord contains the 7th scale degree, which wants to resolve up to the root. This creates a powerful gravitational pull toward the tonic.

Louis Armstrong revolutionized jazz with his innovative approach to melody and harmony. His recordings with the Hot Five and Hot Seven bands showcased new ways of using chord progressions, particularly in his famous solos that would influence generations of musicians.

Duke Ellington brought a more sophisticated approach to jazz harmony. His compositions featured complex chord progressions and extended harmonies that would influence both jazz and popular music for decades to come.

The 1920s saw the introduction of extended chords (7th, 9th, 11th, 13th) into popular music. These "color tones" added richness and sophistication to chord progressions, creating the distinctive sound of jazz.

Jazz musicians began experimenting with chord substitutions, replacing standard chords with more colorful alternatives. This practice, known as reharmonization, became a hallmark of jazz and influenced all subsequent popular music.

The innovations of 1920s jazz continue to influence music today. The ii-V-I progression is found in countless pop, rock, and R&B songs. The concept of extended chords and chord substitutions has become standard practice in modern music production.

The 1920s jazz revolution fundamentally changed the course of music history. The introduction of the ii-V-I progression, extended chords, and sophisticated harmony created a new musical language that continues to influence all genres of popular music today. Understanding these innovations is essential for any musician who wants to understand the roots of modern harmony.