If you have ever seen a 1960s concert poster with a dreamy woman, a halo of ornament and lettering that swirls into hair, you have seen the ghost of Alphonse Mucha.

Mucha was a Czech artist working in Paris who became famous almost overnight in 1895 with a poster for the actress Sarah Bernhardt. His style — elegant women, flowing hair, flowers, mosaics and halos — became one of the signature looks of Art Nouveau. Zodiac, from 1896, was designed as a calendar for the magazine La Plume.

Seventy years later, artists in San Francisco designing posters for the Fillmore and the Avalon Ballroom pored over Art Nouveau books and took Mucha's curves, halos and decorative borders, then turned up the colour until it vibrated. The line from Belle Époque Paris to the Summer of Love is surprisingly direct.

Mucha wanted beautiful things to be affordable. Posters were his answer: art pasted on walls, free to anyone walking past. It is an idea the 1960s would have loved.