73.1First principle — transitions need continuity and change

Suppose Section A ends in C major.

Section B begins in E♭ major.

If you change:

• key
• register
• groove
• texture
• tempo feel
• bass pattern

all at once,

the transition may feel abrupt.

That may occasionally be desirable.

But for a smooth transition, preserve something:

• one pitch
• one rhythmic motif
• one bass note
• one voicing shape
• one melodic fragment
• one subdivision

Something must act as glue.