No text, but a visual code

[ololololo]

The idea that the author painted the plants blue because he had an excess of blue paint seems to me a very poor explanation that ignores the medieval mentality.

Yes, people in the Middle Ages thought differently, but that doesn't mean that everything they did was perfect, accurate, or meaningful.

 This interpretation is a widespread error.

Why?

Also I would like to see a serious argument as to why you might be right, and this argument should be stronger than "blue means space, plants are blue, so plants mean space."