judaism the faith it is today? were the sages the people that set all the guidelines for judaism explaining how a jew should live as well as explaining about the rules by giving their own interpretation of the rules which i guess to an extent to varying degrees influence modern day rabbis when deciding how people in their community should live as well as when giving advice on jewish issues
also how did the the sages find out about all the rules, i assume they were passed down the generations and they thought that they should write them down as well as explain them
also how did the the sages find out about all the rules, i assume they were passed down the generations and they thought that they should write them down as well as explain them