In 1827, Berlioz attended a performance of Shakespeare’s Hamlet given by a troupe of British actors at the Odéon Theatre in Paris. There, the 24-year-old composer became infatuated with the Ophelia of the production, an Irishwoman named Harriet Smithson.
The composer had to find an outlet for his obsessive love – naturally, that was music. He formed the idea of a “fantastic symphony” portraying an episode in the life of an artist who is constantly haunted by the vision of the perfect, unattainable woman.
In Symphonie fantastique Berlioz imagines himself, the lovelorn artist, attempting suicide by opium poisoning. He doesn’t administer a lethal dose as intended, but instead succumbs to a deranged, drug-fueled dream in which he has killed his beloved and faces execution for the crime.
By now recoiling from his obsession with Smithson, Berlioz fell in love with a nineteen-year-old pianist, Marie ("Camille") Moke. His feelings were reciprocated, and the couple planned to be married. In December Berlioz organised a concert at which the Symphonie fantastique was premiered. Protracted applause followed the performance, and the press reviews expressed both the shock and the pleasure the work had given. Berlioz's biographer David Cairns calls the concert a landmark not only in the composer's career but in the evolution of the modern orchestra. Franz Liszt was among those attending the concert; this was the beginning of a long friendship. Liszt later transcribed the entire Symphonie fantastique for piano to enable more people to hear it.
Shortly after the concert Berlioz set off for Italy: under the terms of the Prix de Rome, winners studied for two years at the Villa Medici, the French Academy in Rome. Within three weeks of his arrival he went absent without leave: he had learnt that Marie had broken off their engagement and was to marry an older and richer suitor, Camille Pleyel, the heir to the Pleyel piano manufacturing company. Berlioz made an elaborate plan to kill them both (and her mother, known to him as "l'hippopotame"), and acquired poisons, pistols and a disguise for the purpose. But by the time he reached Nice on his journey to Paris he thought better of the scheme, abandoned the idea of revenge, and successfully sought permission to return to the Villa Medici. He stayed for a few weeks in Nice and wrote his King Lear overture.