>>1159931With Ancient Egypt, pictographs could not be read because the writing language had gone extinct thousands of years ago. However, the Rosetta stone, which held a decree written in three languages, Old Greek (which we knew), common pictograph (which we didn`t know) and heiroglyphs (which we also didn`t know). Through this stroke of luck we finally understood. However for other civilizations which did not cross-translate this is not possible, and their knowledge, beliefs, and cultures will be gone forever; unless we invent some crazy universal translator.