In the course of a lengthy lecture in The Da Vinci Code, given by the historian Teabing and the “symbologist” Langdon to the befuddled detective Sophie, the supposed truth about Leonardo da Vinci’s The Last Supper is revealed.

Viewing a reproduction of the painting, Sophie — prodded by the two scholars — realizes the person seated to the right of Jesus is a woman. She believes she sees feminine hair and hands “and the hint of a bosom. It was, without a doubt ... female. ‘That’s a woman!’” (page 243). Teabing explains that this “glaring discrepancy” is missed because viewers have such a powerful preconception about the painting that the truth it depicts is overlooked.

In other words, only certain special people, with a sort of gnosis (secret knowledge), can see “the truth” about the work.

Novelist Dan Brown has explained in interviews that he was first exposed to this “fact” while attending an art school in Spain.

Brown’s instructor taught that there is no chalice depicted in the painting, but the “Holy Grail” is actually seated next to Jesus: the person of Mary Magdalene. Brown’s story about his art class may be true, but there is little doubt where most of his “insights” into the painting came from: The Templar Revelation, written by Lynn Picknett and Clive Prince, especially the first chapter, “The Secret Code of Leonardo Da Vinci.”

Interviewed by ABC in November 2003, Brown repeated his character’s assertion that people see what they are told to see: “Our preconceived notions of this scene are so powerful that our mind blocks out the incongruity and overrides our eyes.” The person to Jesus’ right, Brown insisted, is “clearly a woman,” echoing his novel: “It was, without a doubt ... female” (see page 243). How ironic that Brown insists that we see what we are told to see — and then tells us what to see!

Unfortunately for Brown, virtually no art historians or scholars agree with him. Leo Steinberg, widely acclaimed as one of America’s finest art historians, is the author of Leonardo’s Incessant Last Supper (Zone Books, 2001), a masterful and detailed examination of the famous painting. Steinberg explains that St. Andrew (viewed from left to right) “is followed by Peter, Judas and John, the three whose identity in the mural was never doubted.”

In fact, these three have distinctive qualities: Peter’s intense movement forward and wielding of the knife (prefiguring his use of it in the Garden later that evening), Judas recoiling and grasping the bag of money (he was the treasurer for the group), and John’s youthful appearance and contemplative pose.

There is also physical evidence of who was who in the painting. A parish church of Ponte Capriasca near Lake Lugano contains a mid-16th century fresco copy of The Last Supper. On that fresco are the names of the 12 apostles, left to right.

The grouping of John, Judas and Peter is purposeful.

The group [of three] at Christ’s right, John, Judas and Peter”, Steinberg points out, “clusters the three who are destined for roles in the Passion.”

Judas betrays Jesus, Peter denies Jesus, and John — “the disciple whom Jesus loved” (John 13:23; 19:26; 20:2; 21:7, 20) — was the only apostle to stand at Jesus’ cross (John 19:26-7).

Steinberg notes there are also “significant pairs” in the painting, including Peter and John, and Jesus and John. Peter and John are often companions (cf. Luke 22:8), personify “the active and contemplative life” and are “shown putting their heads together.”

Hearing Jesus’ prophecy of impending betrayal, Peter lunges forward in amazement and anger. John is the quiet, reflective contemplative who internalizes the distressing news, his hands folded in a prayerful manner appropriate to the coming death of Jesus. These two true apostles frame Judas, the traitor, who personifies greedy disloyalty. Although there is a large space between Jesus and John, their mirrored images indicate that they are, Steinberg explains, “soul mates ... matched in outline, in (original) hue of garment and tilt of head.”

Viewing the reproduction, Sophie sees “flowing red hair, delicate folded hands, and the hint of a bosom” (page 243). The figure is undoubtedly effeminate, as Leonardo depicted the youthful John in the early-16th century Florentine style. This approach can be seen in other paintings of the period, including Leonardo’s own Saint John the Baptist, which depicts a young man who is effeminate in appearance and also has flowing hair and delicate hands.

Leonardo’s sketches or writings never suggest that the figure to the right of Christ is Mary Magdalene. But they contain evidence that it is the Apostle John. In a sketch for the painting, Leonardo depicts John leaning over, with his face down and with Christ resting an arm on John’s back. Always looking for new ways to depict character and interrelationships, Leonardo opted to show the Apostle John as a mirror image of Christ and to dramatically isolate Christ against the open window behind him.

What about the chalice?

The absence of a large chalice boldly identified as the Holy Grail is important only if we assume that’s what the scene should include. But why should we assume that Leonardo would depict Jesus’ cup any differently than that used by the apostles? In fact, an examination of the painting reveals that each of the figures, including Jesus, has a cup and a piece of bread before them; Jesus’ cup is next to his left hand, his right hand raised over the bread.

Who to believe: a novelist relying on conspiracy theories or 500 years of scholarship? The answer should be as obvious as the real identity of the person seated to the right of Christ in The Last Supper.

Carl E. Olson is the co-author, with Sandra Miesel, of The Da Vinci Hoax: Exposing the Errors in The Da Vinci Code (http://www.davincihoax.com), published by Ignatius Press. He is the editor of IgnatiusInsight.com.