"Solid glass or crystal, whether shaped like an orb or a lens, produces magnified, inverted, and reversed images," writer Walter Isaacson explains in his biography of da Vinci. "Instead, Leonardo painted the orb as if it were a hollow glass bubble that does not refract or distort the light passing through it."

It's an especially strange choice given the artist's otherwise careful — and scientifically accurate — depiction of light in his works. That said, Isaacson, and many others, still believe that the painting is authentic. Perhaps, some have argued, da Vinci intentionally ignored physics in order to highlight Christ's divine powers.

The Guardian article is also now the subject of a legal complaint made on behalf of Christie's International Plc, the auction house that is due to sell "Salvator Mundi" later this year on November 15.