At some time between the decline of classical Roman painting and the Renaissance, visual artists rediscovered the real world, and how to depict it.

Figurative painting changed from heavily stylised images like those in Cimabué’s Maestà, painted in egg tempera for the main altar of the church of Santa Trinita in Florence, between 1280-90.

In little over two hundred years, Raphael’s Portrait of Pope Leo X with Cardinals Giulio de’ Medici and Luigi Rossi, painted in oils in 1517-19, couldn’t be more different.

Landscapes too were transformed. Giotto painted his fresco of the Exorcism of the Demons at Arezzo in 1299, a decade or so after Cimabué’s Maestà above.

Although painted nearly six centuries later, Alfred Sisley’s view of Moret Bridge in the Sunlight, from 1892, is a complete contrast with its accurate perspective projection, shadows and reflections.

A great deal more changed in those paintings beyond three-dimensional perspective projection, including

• representation of the textures and optical properties of surfaces,
• inclusion of self-shadow created by the lighting of form, and of cast shadows,
• reflections and other optical effects.

There’s an extensive literature on some aspects of these changes, but little considers the practical challenges to artists.

Until well into the nineteenth century, the great majority of paintings, including landscapes, were painted in the studio. Pierre-Henri de Valenciennes was unusual in that he collected hundreds of oil sketches he made in front of the motif, like this of Farm Buildings at the Villa Farnese: the Two Poplar Trees, made in Rome in 1780. He used this library of images to compose his studio landscapes, which might explain why the two poplar trees here cast no shadows, as those were details that he would add in the studio according to the light in the painting.

Before the end of the nineteenth century, workshops and studios had limited lighting. To avoid the problems posed by direct sunlight, most relied on more diffuse natural light from the north (in the northern hemisphere). For figurative painting, the most intense light available was the oil lamp. Models were often painted singly, and not in the group to appear in a painting. This made it difficult if not impossible for artists to see the shadows that one figure might cast on others in a group. It’s therefore unsurprising that the great majority of figurative paintings don’t feature optically accurate cast shadows.

For each of the four properties required in realism, artists needed

• reliable and accessible knowledge, such as accurate published accounts of perspective projection;
• practical techniques, such as geometric construction using one- and two-vanishing point models;
• suitable materials and equipment, such as tack-and-line methods to provide construction lines in paintings;
• incentives from patrons and others to take the time and effort.

The advent of photography during the nineteenth century was a help for those artists prepared to learn how to get the most from it. But like so many older optical devices, including the camera obscura, it was only an aid and not an answer.

This photograph appears to show Jules-Alexis Muenier painting the huge finished version of Awakening, with his son Pierre behind him. They’re in a beautifully furnished bedroom, which Muenier was using as a studio. His palettes, brushes, and other equipment all give this an air of truth, except that the artist is dressed immaculately in a clean suit, and there are no sheets or other protection on the floor around the canvas. It all looks too neat and clean.

In this series, I’ll trace the development of each of those four properties, how knowledge has developed and been propagated, how painters could apply it, and what benefit it has had on visual art. Rather than telling what artists should have done, I’ll explain how and why they did what they did.

I hope you’ll join me in the coming weeks as I travel the hard road to realism.