In his book, Colour: Seeing, Experiencing, Understanding, Swiss author Ueli Seiler-Hugova wrote, “[Yellow] is the colour which is closest to light. We associate the rays of the sun and the stars with it. It is the radiance of the spirit ...” The power of colors is that there is often meaning ascribed to them, and yellow is no exception. Arising from the Old English word geolu, yellow can symbolize anything from joy to cowardice to imagination. But it's had a bumpy history along the way. Here are six facts about the color yellow.

1. Yellow was the color of gods and royalty centuries ago.

If you were to travel back to the ancient empires of China, you'd find that yellow was a color specifically meant for royalty. During the Tang dynasty, it was decreed that only emperors could wear chihuang, a reddish-yellow that represented the sun; commoners were forbidden from donning the hue. The Qing dynasty, which was in power from 1644 until the early 20th century, imposed a similar mandate on "imperial yellow," a brighter shade of the color reserved for the emperor and his court. And in Ancient Egypt, yellow represented anything that was eternal and indestructible, such as the sun or the gods themselves, who were often depicted as having gold skin.

2. Yellow is linked to happiness in modern times.

According to CNN, the color yellow was used as a way to treat depression and boost moods as early as 1917. During World War I, a color researcher named Howard Kemp Prossor designed hospital rooms meant to calm the nerves of shell-shocked troops. These rooms had ceilings that were sky blue, floors that were grass green, and walls that were yellow like the sun. Though the cheerful effects were noted by army staff, it wasn't deemed a fitting substitute for more conventional therapies.

There is some science-backed evidence that points to yellow as an inherently positive color, though. In 2010, researchers at the University Hospital South Manchester created a color wheel consisting of black, white, gray, red, orange, yellow, green, blue, purple, brown, and pink. From there, they asked around 520 participants—300 “healthy” participants who didn't experience depression or anxiety and 220 who did—to pick a color that defined them. Not only did most people in both groups choose yellow as the color they were most drawn to, but a majority of the “healthy” participants also chose it as the color that best represented their mood.

3. Yellow is also the color of controversy.

While we may consider yellow to be a positive color today, it used to be associated with radicalism, decadence, and wickedness. In Victorian England, a magazine called The Yellow Book, which ran from 1894 to 1897, covered controversial French art and novels that were deemed too risqué and unsavory for the British public. Both the magazine and the novels employed striking yellow covers, leading many to associate the color with scandal during this period.

When author Oscar Wilde was arrested for gross indecency for his relationship with a male aristocrat in April 1895, it was reported he was carrying the magazine on him at the time. Though this was later discovered to be false (it was actually a copy of the controversial French novel À rebours), that didn't stop the public from marching to the magazine's offices and throwing stones through the windows. In The Yellow Book, Quintessence of the Nineties, author Stanley Weintraub explains that:

“The colour of The Yellow Book was an appropriate reflection of the ‘Yellow Nineties’ a decade in which Victorianism was giving way among the fashionable to Regency attitudes and French influences; For yellow was not only the décor of the notorious and dandified pre-Victorian Regency, but also of the allegedly wicked and decadent French novel.”

In the late 19th and early 20th centuries, the racist term yellow peril was coined to describe what some believed to be the dangers Asian countries posed to the West. In her book, The Culture of Yellow, author Sabine Doran explains how the term—originally coined by Kaiser Wilhelm II—was meant to target both the Japanese military expansion in the years leading up to the Russo-Japanese War and the increasing number of Chinese and Japanese citizens emigrating to Western countries.

Then there's yellow journalism, a late-19th-century term meant to describe news outlets that focused on sensationalism over facts and context. The name came from the feud between Joseph Pulitzer's New York World newspaper and William Randolph Hearst's New York Journal over The Yellow Kid, a popular comic character at the time that both papers laid claim to. When the papers started giving more page space to their competing comics rather than the news itself, the term Yellow-Kid journalism, and later just yellow journalism, was born.

4. Blonde hair might get you more tips.

Maybe Rod Stewart was right that blondes have more fun, because a 2014 study [PDF] found that waitresses at a Philadelphia sports bar saw higher tips when they dyed their hair from brunette to blonde for 30 days. As part of the study, a naturally blonde waitress also dyed her hair brunette and actually saw a decrease in her tips as a result. The study was taken across 282 work shifts and 8000 tables served. While there isn't a conclusive reason for this, there are a few studies out there that found a link between blondes and perceived beauty. One study by researcher Nicolas Guéguen found that even a blonde wig was enough for a woman to attract more attention at a nightclub when compared to her brunette and redheaded counterparts.

5. The combination of red and yellow might make you crave French fries.

Have you ever wondered why so many restaurants like Burger King and McDonald's have yellow and red in their logos? Turns out there's some color psychology at play here. Though there's no conclusive evidence behind it, some research suggests the color red can actually stimulate a person's appetite, while yellow is meant to give off feelings of comfort, according to Metro. This is known as the Ketchup and Mustard Theory, and it's apparently the perfect color combo to make someone crave a greasy burger and some soul-soothing fries.

6. Pink Used To Be Yellow.

Turns out that pink used to refer to a yellowish-green hue as far back as the 1400s. Some believe the word is derived from pinkeln, a German word for urination. It was also sometimes called English pink or Dutch pink, which Merriam-Webster describes as “a light yellow that is greener and slightly darker than jasmine and greener and stronger than average maize or popcorn.” Pink would make the transition to mean its current “pale rose color” by the 18th century, though why it made the switch remains a mystery.