How does the minuet and trio demonstrate ternary form?

The minuet and trio is a quintessential example of ternary form, which is a three-part musical structure organized in an aba pattern.1

In this scheme, the movement is divided into three distinct sections:

• Section A (Minuet): The opening section, which is a complete musical statement ending on an authentic cadence.1
• Section B (Trio): A contrasting middle section, historically performed by three instruments, that is usually written in a different key to provide variety.12
• Section A (Minuet): The final section, which is a repeat of the initial minuet. This return is often indicated by the term da capo ("from the head"), though it may be written out in full if the composer chooses to vary the material.1

Each section within the minuet and trio is relatively self-contained, typically comprising at least a period or double period. This symmetrical construction creates the balanced, three-part shape that defines ternary form in Western music.1