“As with sounds, so with colours. At each end of the solar spectrum the chemist can detect the presence of what are known as ‘actinic’ rays. They represent colours — integral colours in the composition of light — which we are unable to discern. The human eye is an imperfect instrument; its range is but a few octaves of the real ‘chromatic scale.’ I am not mad; there are colours that we cannot see.”

There was no sound and at first I could see nothing but nitre-encrusted walls and wet stone floor. Presently, however, in a far corner, just beyond the flickering halo of the faggot torch, I saw two tiny, fiery spots of red. I tried to convince myself that they were two red jewels, two rubies, shining in the torchlight.

But I knew at once – I felt at once – what they were. They were two red eyes and they were watching us with a fierce, unwavering stare.–Joseph Payne Brennan