• The most futuristic debates – Can a mikvah be built on the International Space Station? May metals from Mars be used to build a mikvah?
• The oldest debate on record, between Yitzchak Avinu and the shepherds of Gerar - 3,600 years ago, the question was: how can you tell if a mikvah’s water comes from a nearby river or from some other source?
• The most controversial debate - 400 years ago, in Rovigo, Italy, the brothers Consiglio argued how to fill the mikvah in their yard: and before the debate was over, rabbis from across the world, from Eretz Yisrael to Prague, had authored hundreds of pages in defense of each side!

This sefer explores how these debates (and others) shape our understanding of the nine basic rules for building a mikvah; how they inspire and enlighten us about the importance of purity and immersion; and how they enhance our relationship with Hashem.