At the Salon in Paris is 1895, Joaquín Sorolla y Bastida (1863–1923) had enjoyed continuing success with his Naturalist paintings, including Return from Fishing (1894), which won him a gold medal, was bought by the French state, and now graces the Musée d’Orsay.

Sorolla continued to paint scenes from the working lives of fishermen in Valencia, including their shore maintenance tasks in Fishermen Taking up Nets (1896).

That year he also painted the better-known Sewing the Sail. This shows a scene on a patio at El Cabañal beach, Valencia, during the Sorolla family holiday in the summer of 1896. Although it may look a spontaneous study of the effects of dappled light, Sorolla composed this carefully with the aid of at least two drawings and a sketch, which survive. It shows the whole family engaged in one of the more technically-challenging supporting tasks ashore.
This was exhibited the following year at the Salon in Paris, where it was praised, and went on to win first prizes in Munich and Vienna. Reaction was more mixed when shown in Madrid in 1899, but at the 1905 Venice Biennale it was bought by the city of Venice in recognition of its popularity there.

Sorolla’s Portrait of Dr. Simarro at the Microscope from 1897 shows Doctor Luis Simarro Lacabra (1851-1921), who was an eminent psychiatrist in Madrid. He also undertook pioneering research looking at the fine structure of the brain. Among his many achievements was a modification of an established technique for staining microscopic sections of brain, which proved a major advance and an inspiration to the great Spanish neurohistologist Ramon y Cajal. This portrait was exhibited at the National Exhibition in Madrid in the same year.

Research, or under its original Spanish title of Una investigación o El Dr. Simarro en el Laboratorio, from the same year, goes on to look at Dr. Simarro at work in the laboratory among colleagues and students. He is here preparing specimens for microscopy, presumably using his staining technique. The table is covered with bottles of chemicals used in that process, and the chunky metal object in the centre foreground is a microtome, used for cutting very thin sections of tissue embedded in paraffin wax, prior to their staining, for study under the microscope.
These two paintings are probably his most floridly Naturalist works, celebrating contemporary advances in science, technology and medicine, in a documentary style.

Sorolla’s best-known painting from his Naturalist period is his large Sad Inheritance (1899), which won him the Grand Prix and medal of honour at the 1900 Exposition Universelle in Paris, and a medal in Madrid the following year. As ever, its spontaneity is deceptive: this is one of his most carefully-prepared paintings for which at least oil sketches survive.
This shows a group of young boys from a local charitable hospital enjoying a visit to the sea in the care of a ‘lone priest’, and celebrates the mission of the Hospitaller Order of St John of God, who had built the hospital in 1892 at the end of Malvarrosa Beach. Sorolla later said that he had witnessed this scene one evening in a remote corner of the beach, and once he had been given permission to paint the boys, he made an initial oil sketch from memory.
There is considerable dispute over the cause of the boys’ disabilities. Sorolla’s title implies that they result from the ills of society, implying conditions such as congenital syphilis, and the consequences of parental alcoholism. More consistent with the period and their appearance, though, would be a mixture of preventable conditions including polio, which wouldn’t have fitted as well with the artist’s social message. Whichever was true, the implicit criticism made of the state left this remarkable Naturalist painting unsold, despite its medals and awards.

Although Sad Inheritance was Sorolla’s last large Naturalist painting, he continued to create works in similar style. Lunch on the Boat, painted in the previous year, shows a group of Valencian men and boys eating an improvised lunch under the awning on their fishing boat.

His later large Afternoon Sun, Beaching the Boat (1903) is another scene of fishermen working hard with three teams of oxen to bring a fishing boat ashore, in the spirit of Return from Fishing.

Beach of Valencia by Morning Light from 1908 shows mothers taking their children into the water on El Cabañal beach, Valencia.
In May 1908, Sorolla had a spectacular solo exhibition of 278 works in the Grafton Galleries in London, sponsored by his friend John Singer Sargent. Although not a commercial success, it was visited by Archer Milton Huntington, an American philanthropist who had founded the Hispanic Society of America in New York just six years earlier. In 1911, Huntington commissioned Sorolla to paint fourteen huge canvases to cover the walls of the society’s library, which became the cycle Visions of Spain. For these, Sorolla returned to Naturalism.

Castilla, The Bread Festival (1913) shows the pageantry of a local festival in the province of Castilla. The section here is just over half of the full width of this part, which is just under 14 metres across.

Ayamonte, Tuna Fishing (1919) is a section from another painting in this series, showing the tuna market in the town of Ayamonte, Spain, which must have reminded Sorolla of his Valencian summers.
Véronique Gerard Powell has made an excellent point. It should (with the wisdom of hindsight) have been obvious that Sorolla painted Naturalist works for a period of more than a decade. And several of them remain among his very best.
Reference
Véronique Gerard Powell (2019) Sorolla and ‘social painting’, in Sorolla, Spanish Master of Light, National Gallery and Yale UP, ISBN 978 1 85709 642 2.