Why purple became the colour of kings and creativity

Psychologically, purple and blue flowers are often seen by us as exotic and elegant. Their rarity in some landscapes, such as the purple heathers commonly found in moorlands, mountainous bogs, and lowland heathlands, makes them stand out, most famously across the Scottish highlands. Our cultural associations with purple link the colour to royalty, mystery and creativity. These associations also affect our decisions to buy purple plants.

But there’s a deeper ecological twist to the story of purple. Flowers evolved to be seen by pollinators like bees and butterflies. But pollinators do not see the world the same way we do. Our sight evolved to see a wide range of different colours but many insects have photoreceptors tuned to ultraviolet (UV) light as well as to blue and green. They can’t see purple the way humans do, what the insects ‘see’ are patterns and contrasts in UV light that are invisible to us.

The signals flowers send have evolved for pollinators’ vision, not ours, and purple often carries strong, high-contrast cues in the UV and blue parts of the spectrum that are especially attractive to pollinators. The co-evolution of flowers naturally selecting colours that appeal to the sensory worlds of pollinators helps explain why purple blooms are so arresting to us. They are doing double duty, appealing to both pollinator perception and human aesthetics. So we plant more blue and purple flowers. In summer, lavender bushes attract lots of bees, busy gathering pollen and nectar to make delicious honey.

Decades of research in colour psychology reveal to us that different hues and colours can influence mood and behaviour in subtle but measurable ways. Purples tend to be associated with calmness, creativity and a sense of luxury or mystery, sitting psychologically between the cool stability of blue and the passionate warmth of red. Experimental studies and reviews report consistent links between purple and feelings of introspection and imagination. Because of this, designers often use softer lavenders to soothe and deeper violets to signal richness. These effects are not absolute though; context, cultural background and individual differences matter but the pattern is robust enough that architects, advertisers and therapists take it seriously.

The imperial weight of purple has a long pedigree. In the ancient Mediterranean, the most prized purple was Tyrian purple, named for the Phoenician city of Tyre. The dye was extracted from the mucus of sea snails in the genus Murex; the process was laborious and the yield tiny, so the colour became a marker of extreme expense. By the time Rome absorbed the eastern Mediterranean, purple had been woven into the language of power. Roman law and custom regulated its use: certain shades and garments were reserved for magistrates and emperors, and the toga picta or the imperial purple cloak signalled office and divine favour. The association was partly practical as scarcity breeds prestige but it was also symbolic. Purple’s rarity made it a visible shorthand for authority. Its deep, almost bloodlike tones suggested permanence and gravity, qualities an emperor wanted to project.

How, exactly, though did the ancients make that colour? Tyrian purple was not a single recipe but a group of related processes. Workers collected thousands of Murex snails, cracked the shells, and extracted a small gland. The gland’s secretions, when exposed to sunlight and air and then treated in vats, underwent chemical changes that produced a range of purples and reds; the most prized shades were a deep, enduring purple that resisted fading. The scale of the operation, vast numbers of snails, large dyeworks, and skilled artisans, helped keep the price high. Modern chemical analysis of archaeological textiles and residues has confirmed the molluscan origin of many ancient purples and shown how different processing steps and species produced subtly different hues.

The story of purple, however, took a decisive turn in the nineteenth century with the arrival of synthetic dyes. In 1856 a young chemist, William Henry Perkin, accidentally produced a purple substance while attempting to synthesise quinine. The compound, mauveine, could be manufactured from coal-tar derivatives and dyed fabrics a vivid purple at a fraction of the cost of Tyrian purple. Perkin’s discovery inaugurated the chemical dye industry and democratised purple. What had been the preserve of emperors and the very wealthy became available to the middle classes. The industrial production of mauveine and subsequent synthetic dyes transformed fashion, commerce and even politics, suddenly colour was no longer only a sign of birth or rank but of taste and trend.

Dr James Williams is an emeritus reader in science education and communication at Sussex University.