Books · 1957
In Who-ville they say That the Grinch’s small heart Grew three sizes that day!
— Dr. Seuss · How the Grinch Stole Christmas!

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The narrator reports what the townsfolk say: a stingy, shrunken heart expanded enormously in a single day. The lines are warm and lightly comic, celebrating a sudden change of heart as something almost measurable, a transformation big enough to count in sizes.
Context reviewed