The text discusses the use of PostgreSQL's recursive common table expression (CTE) to traverse hierarchical data and solve problems like the "Bacon Numbers" problem. It explains how YugabyteDB, a distributed SQL database, re-uses the PostgreSQL source code to provide SQL and stored procedure functionality. The author uses examples, including an employee hierarchy and the Bacon Numbers problem, to illustrate the use of recursive CTEs in solving these types of problems. The text also covers the syntax and semantics of the WITH clause and common table expressions (CTEs) in YugabyteDB's YSQL documentation. It provides code snippets and explanations of how to implement recursive CTEs using YugabyteDB's YSQL, including examples of breadth-first and depth-first traversals of a hierarchy. The author concludes that the power of PostgreSQL's recursive CTE is awe-inspiring and invites readers to learn more in Part Two.