Why the Greek and Roman drawings and paintings of people appear much rudimentary?

Why was it that the Greeks and Romans of antiquity were able to sculpt perfect human forms, yet their drawings and paintings of people appeared much more rudimentary?

Below is a Greek sculpture called “Laocoön and His Sons” and dated sometime during the Hellenistic Period, c. 323 BCE – 31 CE.

Meanwhile, this is a painting from the same time period (c. 2nd century BCE). We understand that this is only one example amongst thousands, but why is there such a distinct difference in forms? Was there a challenge extant with two dimensions that weren’t present in three?

The Greeks and Romans themselves saw no distinction between the accomplishments of painting and those of sculpture. The greatest painters, like the most eminent sculptors, were famed for their ability to capture life in every ineffable detail.

Sometime around the beginning of the fourth century BC, the great Greek painters Zeuxis and Parrhasius had an art contest. As Pliny tells it:

“Zeuxis produced so lifelike a representation of grapes that birds flew up to the stage building where it was hung. Then Parrhasius produced such a successful image of a curtain that Zeuxis, puffed up with pride about his birds, asked the curtain to be drawn aside and the painting revealed. When he realized his mistake…he conceded the prize, saying that while he had deceived birds, Parrhasius had deceived an artist.” (35.65)

There are many other anecdotes about the astonishing level of verisimilitude achieved by other great artists (Apelles and Protogenes, for example, had a similar contest). For our purposes, the important point is this: the Greeks and Romans never viewed painting as an inferior medium, and attributed almost photographic realism to the greatest painted masterpieces.

So: why do the ancient paintings we possess seem inferior to the greatest classical sculptures? To an extent, the problem is often an apparent failure to use scientific perspective, making the scenes and figures appear flat and cartoonish. Sometimes, as in vase painting, this is just a consequence of convention. In frescoes, it tends to be a failure of the artist, not his technique.

When they wanted to, the Greeks and (especially) the Romans were perfectly capable of creating impressively three-dimensional scenes. Roman Second Style paintings, for example, often evoke whole monumental cityscapes.

The most basic reason for the perceived inadequacies of ancient painting, however, is the simple fact that all of the masterpieces have vanished. Thanks to the Roman practice of producing copies of Greek sculptures, we have at least a general idea of the appearance and accomplishment of the greatest accomplishments in that medium.

But with the exception of the frescoes of Pompeii and Herculaneum (and, to a lesser extent, mosaic copies scattered across the Roman world), ancient painting is lost to us.

Most Pompeiian frescoes are not masterpieces. They were never meant to be. They were the functional equivalent of wallpaper, rendered rapidly by teams of painters working from pattern books. The same is true of most tomb paintings, such as the example given in the first paragraph. But when the artists were exceptionally talented or exceptionally careful, we can still catch glimpses of the lost masterpieces of ancient painting. Take, for example, the famous frescoes of the Vergina tomb, or the Alexander mosaic from Pompeii (a reproduction of a lost painting by the great Apelles). At least some classical artists could work wonders in two dimensions.