If on any given Monday in Bangkok you realize that all around you everyone is dressed in yellow, have no fear: it’s a tribute to the king.

The relationship between yellow and the aristocracy has been alive for centuries, above all in African nations, where it’s considered an acceptable stand-in for the splendor of gold.

This similarity yellow has with gold can also be used as a form of trickery: in the tenth century in France, doors of criminals and traitors were painted yellow. It’s no coincidence that Judas in the bible wore a yellow cape.

In China, a yellow book means it’s pornographic, while in the United States yellow is the traditional color of taxis and school buses. In Germany, yellow means envy, and in Japan it’s associated with courage.

For most western countries, yellow represents optimism and summer. Ask a child to draw the sun, he or she will know which crayon to use.