96. Read the following passage, then answer the question below.

In July 1799, French soldiers repairing a fort near the Egyptian town of Rashid, known to Europeans as Rosetta, unearthed a slab of dark stone covered with writing. The slab carried the same decree, issued in 196 BCE in honor of the young king Ptolemy V, in three scripts: Egyptian hieroglyphs, a cursive Egyptian script called demotic, and ancient Greek. Scholars could read Greek, so they realized at once that the stone might provide a key to hieroglyphs, which no one had been able to read for about fourteen hundred years. After Britain defeated the French in Egypt, the stone passed to the British under the terms of the surrender and has been in the British Museum since 1802.

Progress was slow. For centuries many scholars had assumed that hieroglyphs were purely symbolic pictures that expressed ideas rather than sounds. The English physician Thomas Young, working from the Greek text, identified the oval rings called cartouches as containing royal names and correctly matched some signs with sounds in the name Ptolemy. But Young believed that phonetic signs were used only for foreign names. The decisive breakthrough came from the French scholar Jean-Francois Champollion, who knew Coptic, the last stage of the Egyptian language, and used it to guess the sounds behind the signs. In 1822 he announced that hieroglyphs combined phonetic signs with signs standing for whole words or ideas, and that this system had been used for native Egyptian words too.

The decipherment opened thousands of years of history. Temple walls, tomb paintings, and papyri could finally be read as the Egyptians had written them, rather than through the filtered accounts of Greek and Roman authors. Yet the stone itself remains a subject of controversy: Egypt has requested its return, arguing that the stone was taken under imperial circumstances, while the museum maintains that it was acquired legally under the treaty.

What mistaken belief did Thomas Young hold?