Explanation

This carol text follows a specific melody pattern. The tonic sol-fa shows which notes to sing and how long.

The pattern m:m|m:f|s:-|m:-|f:f|r:t|d:-|-:-|| matches the melody perfectly. Each symbol shows note duration and pitch changes.

Tonic sol-fa uses letters like d, r, m, f, s to show pitches. Colons and dashes show rhythm and rests.