As he thought about the hieroglyphs in Thothmes' and Ramesses' names, Champollion realized their significance. It went far beyond the names themselves and gave him an insight into the entire system of hieroglyphic writing. For the names revealed that hieroglyphs were not simply representations of sounds. Nor did they have an exclusively symbolic meaning, as Thomas Young and other scholars had long believed. Instead, they were a combination of the two.

—The Riddle of the Rosetta Stone,
James Cross Giblin

Based on the passage, what did Champollion discover about the hieroglyphs on the Rosetta Stone? Write one to two sentences explaining his discovery in your own words.