In Koenigsberg in eighteen fifty,
Professor Hermann Helmholtz taught a class,
His students asked him why a cat's eyes glow,
And why a person's pupil looks so dark,
No one could see inside a living eye,
He lit a candle and he stacked glass plates,
They tipped the light into his student's eye,
And let him look along the same straight way.
Come and look into my eyes,
With Helmholtz and his eye mirror,
The candlelight goes in,
And bounces back to you,
With tiny red roads running through.
At first, the inside looked like blur,
So he added a lens to make it clear,
And there it was, for the very first time,
The back of a living eye, so near,
An eye doctor named Albrecht von Graefe,
Looked in, and his face lit up with cheer,
He cried that Helmholtz showed a whole new world,
And soon each eye doctor wanted one.
Come and look into my eyes,
With Helmholtz and his eye mirror,
The candlelight goes in,
You'll see the glowing red inside,
With tiny red roads running through.
That's why a cat's eyes shine at night,
When your porch light falls their way,
The light goes in and bounces back,
Just like Helmholtz showed that day.
Today you sit in a darkened room,
The doctor holds a tiny light,
She looks into your eyes up close,
To check that everything's all right.
Come and look into my eyes,
With Helmholtz and his eye mirror,
The candlelight goes in,
And bounces back to you,
With tiny red roads running through.
Look into my eyes, goodnight.
