Why did societies priests develped considerable social power in River Valley?

Question

Why did societies priests develped considerable social power in River Valley?

Answer 1

which society and which river valley u speaking of specifically?generally the priests were the ones with the smarts or ability to predict the weather, specifically the coming of the seasons, the turning of the year etc. this gave them great symbolic power as well as practical power, for if one can predict the right time of year to plant and harvest, you can greatly increase your people wealth.and for the ordinary schmo, it would have been like magic , for only the priests had teh leisure time to devlop the mathand or tools to enable them to make such predictions. as they gained in predictive accuracy, so they would have gained in their ability to demand tribute from their people.hope that helps in a general way. oh yeah, in the nile valley adn to a lesser extant the euphrates river the ability to predict when the annual floods would occur would have done the same thing.  Later on, predicting astrological events like eclipses wouldnt have hurt their cause either.