Complex sentence: Ramses'ultimate downfall is caused by his underestimation of his opponents and by his impatience with priestly obscurantism: along with the chaff of the priests' myths and rituals, he has inadvertently discarded a crucial piece of scientific knowledge.
Split into simpler sentences: Ramses'ultimate downfall is caused by his underestimation of his opponents and by his impatience with priestly obscurantism. Along with the chaff of the priests' myths and rituals, he has inadvertently discarded a crucial piece of scientific knowledge.