Religious beliefs caused the Egyptians to develop, for their time, a highly advanced system of public health.   Because of their beliefs, the Egyptians paid considerable attention to cleanliness of the body and the home.  Among all economic and social classes washing was to be practiced every morning, evening and before each meal, but because soap had not been invented they used a type of alkali.  The water of the Nile was, at that time, extremely clean and there was a plentiful supply.  The Egyptians devised an elaborate system of canals, dams, and basins to assist their agricultural efforts; however, these low lying water sources became breeding grounds for insects which probably carried malaria and other diseases spread by insect vectors.