Answer:
By solving the Egyptian hieroglyphs.
Step-by-step explanation:
Prior to the discovery of the Rosetta stone, historians could n't fully understood the meaning of the ancient Egyptian writings. The stone consists of inscription that helped the historians solved the Hieroglyphs.
By understanding the Egyptian Hieroglyphs, the historian can decipher various arts that left over by the Egyptian civilization (such as the painting on the walls, the sculpts within the burl , etc.) It basically provide us with information regarding Egyptian's old way of thinking and philosophical knowledge. All of these wouldn't be possible without the Rosetta stone.