It was 30 years ago that Christian Louboutin borrowed his assistant's nail varnish to fix a problematic sole and inadvertently created a design that would make him globally famous.
It was 1993 and Louboutin, then 30, was examining a pink and purple shoe prototype. The black sole was too dominant, he felt, and so called for his assistant.
"I took the nail polish and erased the black. I wasn't thinking to add the red," he recalled to AFP in his brightly decorated Paris apartment.
The earlier idea of releasing a different colour sole each season never materialised.
"People who don't like to wear colours still like red," he said.
"The obsession began with the fact that red is more than just a colour for me.
"I have very early memories of women dressed in black but already with red nails and lips. It began with cinema, the actresses of the 1950s like Sophia Loren."
He marked the 30th anniversary of his famous red sole this week with a dance performance at the Opera Comique and will soon open his first hotel in Portugal named "Vermelho" (Red).
The black stiletto with the red sole remains his best-selling model, despite the range of flats and mid-heels.
He rejects the idea of heels as anti-feminist, saying he delights in seeing customers put on a pair of stilettos and admire themselves "front, profile and back" without caring what their "husband, boyfriend or girlfriend will think".
Or little girls trying on their mother's heels without anyone telling them to, "There is a kind of infantile pleasure in seeing life from a little higher up."
For him, heels are a symbol of female empowerment.
He thinks of Tina Turner in her heyday, or Beyonce now, teetering on heels but incarnating "feminism, much more than someone who lets themselves go".
With the passing of lockdowns and lounging around in pyjamas, it is time to celebrate, he added.
His new collection, inspired by flamenco, sees him collaborate with Rossy de Palma, the flamboyant Spanish star of many Pedro Almodovar movies.
"I like singular people, and there is only one Rossy," he said. "Someone who exudes amusement, pleasure, laughter, everything."