“Well what they did is to paint some squares of cardboard black. A real black, the black of the darkest, most moonless night black. But not just squares but also other shapes, like triangles and circles and rectangles and and stars and circles, oh I said circles already didn’t I, sorry sometimes I get muddled a bit but what they did is paint all these shapes, these circles and squares and rectangles and triangles and stars black. Then they asked people what colour they were.

The people who they asked all said black. So that is how they first knew that black was black. But then they thought of another test. This time they paint all the shapes, the circles, the squares, the rectangles, the triangles, the stars. All those shapes and more. They painted them all red. Red like blood. But not old blood that turns brown. Nor blood that scabs and turns black but fresh blood. Maybe blood is a bad example. They painted the shapes the squares and the circles and the triangles and the stars and the rectangles they painted them all in a red like a rose. A red rose of course. Not a blue rose because that would not make much sense but a red rose. Then they asked the people again.

Do you know what the people said? They said that it was red, not black. So, then they knew that red was not black.

So, this time they painted paper and wood and metal and plastic and the floor and the ceilings and the walls all these things they painted green. They painted them all green in all the shapes in circles and in squares and in rectangles and in triangles and in stars, they painted it all green. Many different colours of green. Green of grass, green of green water, green of melon, green of lime and many other greens. All the wood and paper and metal and plastic and floors and ceilings and walls they painted them all sorts of greens. Then they asked the people again. What colour is this?

The people said green. Green of grass green of melon green of lime green of green water. So green was not black.

So, then they painted all the different shapes the circles the stars the rectangles the triangles the squares they painted them all different colours in reds and greens and purples and blues and oranges and yellows. All the colours they painted them in all the different materials in wood and metal and floor and plastic and ceilings and walls and paper and carboard. Then they asked again what colour is it?

Most of the people said the different colours they said red and green and orange and yellow and purple and blue but some people said the dark blue ones were black but the scientists knew that dark blue was not black, that it was dark blue and not black.

And that is how the scientists proved that black was black.”

Jo sat as the stranger slumped back in her chair. She had no idea who this person was, why they had decided to walk into Jo’s office, to sit down and tell a story but Jo knew that they needed help.

“Would you like a cup of tea dear?” she asked politely.