Niall Ferguson's "The Ascent of Money" explores the historical development of financial systems, highlighting the importance of contracts in facilitating economic transactions. One notable example is the medieval contract called the census, which enabled one party to purchase a series of annual payments from another. This arrangement exemplifies the early forms of income-generating financial instruments that paved the way for modern finance.

The census underscores the intricate relationship between money and contractual agreements in shaping economic practices. By allowing individuals to secure future income in exchange for a lump sum, it reflects an early understanding of financial planning and risk management, showing that the foundations of our current monetary systems have deep historical roots.