Ninety years ago this month a young Russian scientist and inventor, Leon Theremin, was summoned to the Kremlin to meet Lenin. It was the start of an incredible journey that laid the foundations for modern electronic music, from the Beach Boys to Pink Floyd.
Leon Theremin had come to the Bolshevik leader's attention after inventing a revolutionary electronic musical instrument that was played without being touched.
Theremin was nervous before meeting Lenin, but later said the demonstration of his invention, which became known as the Theremin, had gone well.
"Leon Theremin was very impressed by the meeting with Lenin in the Kremlin. He was a young Bolshevik at that time and he was very excited by the changes in the country and he respected Lenin a lot," says his grand-niece Lydia Kavina.
"He saw Lenin as a very intelligent person and Lenin fully understood the wild and new ideas of the young inventor, and also Lenin was very skilled in music and tried to play the Theremin himself and with quite a good success and that impressed Leon Theremin a lot."
The instrument consisted of a small wooden cabinet containing glass tube oscillators and two antennae - one sticking out the side and the other out of the top - which produced electromagnetic fields.
Theremin played Lenin pieces including Saint Saens' the Swan. He then guided Lenin's hands - the right one moved to and from the vertical antenna, changing the instrument's pitch, the left one moved to and from the horizontal antenna, controlling the volume.
Theremin, an amateur cellist, had come up with the idea for his instrument shortly after the Russian revolution in St Petersburg.
He was developing an electronic device for measuring the density of gases and noticed the sound it made changed depending on the position of his hand.
Lenin was so impressed he sent Theremin across Russia to show off his instrument and promote the electrification of the country.
"He went all around Russia and gathered great crowds in squares and in halls and made a sensation," says Albert Glinsky, author of the Theremin biography Ether Music and Espionage.
He was then sent to Europe and the US to showcase Soviet technology and his performances received widespread coverage in the newspapers, with headlines about magical music being created out of the air.
"When he arrived in New York it was to great fanfare and he was celebrated as one of the great scientists and his invention was hailed as the equal of radio," Glinsky told the BBC World Service.
He performed at Carnegie Hall. His instrument also attracted the attention of the Radio Corporation of America, RCA, who offered him what was then the huge sum of $100,000 to manufacture it.
A contract was signed on 12 March 1929, making RCA the first mass producer of an electronic instrument.
"That moment was the beginning of a long progression that comes right up to this day when a young person goes into a store and says 'I want that electronic keyboard for my band,'" Glinsky says.
"RCA felt this was going to replace the parlour piano and anyone who could wave their hands in the air or whistle a tune could make music in their home with this device."
The Theremin went on sale in September 1929 at the relatively high price of $220 - a radio set cost about $30. It was also much more difficult to play than the advertising claimed. And just one month later came the Wall Street Crash.
"You took it home and found that your best efforts led to squealing and moaning sounds. So the combination of the fact that only the most skilled people could teach themselves how to play it and the fact that there was a downturn in the economy meant that the instrument really wasn't a commercial success," Glinsky says.
RCA halted production.
Theremin saw little of the $100,000 he was paid, Glinsky says, which most likely went straight into Soviet coffers. But he stayed in the US for a while working on other projects, and engaging in industrial espionage.
"His very reason for being sent over was his espionage mission," says Glinsky. Demonstrating the theremin instrument was just a distraction, a Trojan Horse, as it were.
"He had special access to firms like RCA, GE, Westinghouse, aviation companies and so on, and shared his latest technical know how with representatives from these companies to get them to open up to him about their latest discoveries.
"He also ran his own companies, which were fronts for industrial espionage, and he reported to Amtorg, the Soviet trading corporation in America, itself a front for espionage activities."
Theremin also developed a prototype drum machine and an instrument that responded to a dancer's movements, alarm systems and an electric door opener, but none of his inventions proved a commercial success, and he ended up in debt.
He met and married a young black American ballet dancer, Lavinia Williams, in 1938. Lydia Kavina says the relationship further compounded his financial problems.
"When he got married to the black woman, this event turned a lot of bankers and his sponsors away from him. It wasn't a time when such a marriage would be acceptable in American society."
Later that year he returned suddenly to the Soviet Union, leaving his wife behind. Some people suggested he'd been kidnapped by Soviet officials, but Glinsky says a combination of debt and homesickness led to Theremin returning voluntarily.
He returned to a Soviet Union in the grip of Stalin's purges. He was arrested and falsely accused of being a counter-revolutionary, for which he received an eight year sentence in 1939.
He was sent to the Gulag in Siberia, but with war looming he was taken back to Moscow and, while still a prisoner, made to work on aircraft technology. He also developed highly advanced bugging devices that were used against foreign embassies.
Theremin was released in 1947 but returned to work for the state security system as a free man, then worked at the Moscow Conservatory where he worked on, and taught his instrument.
In the US, the Theremin had been revived by Hollywood in the 1940s and 1950s. Its eerie sound was used in films such as Alfred Hitchcock's Spellbound and sci-fi classics, such as The Day the Earth Stood Still.
A young Robert Moog, who went on to become a synthesizer pioneer, began making and selling Theremins. He later wrote that it was a "vital cornerstone of our contemporary music technology".
In the 1960s its sound made its way into popular music, most notably in the Beach Boys' song Good Vibrations - though it is believed the group may have used a Theremin-like instrument to mimic the sound, rather than the Theremin itself.
Glinsky says Theremin knew little of what had happened to his most famous invention in the US until shortly before the collapse of the Soviet Union when he was able to go abroad again.
The author met Theremin on his trip to the US in 1991. "He was honoured not only in New York, but he was brought out to Stanford University. I'm sure deep inside he was very grateful to be recognised by people who knew the worth of what he'd one."
Leon Theremin died in Moscow in 1993 aged 97. His invention is still made and played by enthusiasts around the world.