Books have been given as gifts in Barcelona on April 23rd every year since the 1920s when a bookseller on the city's iconic Las Ramblas boulevard started the trend after realizing that the day almost coincided with the deaths of Cervantes and Shakespeare.
The idea took off around the world when UNESCO named April 23rd as World Book and Copyright Day in 1995.
Barcelona is Spain's publishing powerhouse and almost half of the book sales in the autonomous region each year take place on St. Jordi's day.
Because of this, it is a hugely important day for authors who spend the day signing often-discounted copies of their work to huge queues of people.
But sixteen authors have cancelled their planned book-signing marathons in solidarity with staff in Fnac El Triangle, the French-owned department store at the top of Las Ramblas.
The shop dedicates an entire floor to books but instead of the anticipated crowds on Wednesday, photos on social media showed it almost deserted during the key pre-lunch shopping period.
The company brought in temporary staff to cover a 24-hr strike by workers and keep the shop open but were unable to prevent cancellations by celebrity authors.
Big names including Juan José Millás and Enrique Vila-Matas, among many others, were set to appear in Fnac but refused after learning of recent changes to working conditions.
Strike organizers claim that 60 per cent of staff are on part-time contracts and earn less than €500 ($690) per month.
They allege that the company "has virtually eliminated full-time job contracts", according to local daily El Periodico.
Staff are said by union leaders to suffer "stress, an overwhelming workload, abusive behaviour, constant pressure to hit sales targets, control, constant vigilance and an obsessive control of their movements".
Women in Catalonia have received roses on St. Jordi's day since the 15th century, in a romantic tradition similar to that of Valentine's Day. Men now receive books, although it is common for women to receive them as gifts too.