We Cambridge people think things through a bit,

While you make light of light and then switch off.

So photons travel 60 trillion miles,

without much fuel, nearly straight ahead,

while we are merely going round the Sun.

They thread a needle’s eye but are diffuse,

And seem to be quite light, and do not fight.

They give us paintings, colours, tone and line,

and, subtle, bounce some six or seven times.

So did this all evolve, our retinas

from sense cells formed in early slime?

No, this exquisite universe alight,

Was made before the animate was born,

before all eyes had ever come to form.