Legal Definitions - libra

Historically, the term libra referred to an English pound, which could represent either a specific unit of weight or a sum of money equivalent to a pound sterling. It is a historical term for a significant unit of value in medieval and early modern England.

• Example 1 (Weight): In a 14th-century English market, a merchant might agree to sell a bolt of fine wool for "ten libra" of silver, meaning ten pounds of silver by weight.
  Explanation: This illustrates libra as a unit of weight for a valuable commodity (silver) used in trade, where the physical quantity of the metal determined its value.
• Example 2 (Money): A medieval charter might record a donation of "one hundred libra" to a monastery, signifying a gift of one hundred pounds sterling in monetary value.
  Explanation: This demonstrates libra as a sum of money, equivalent to the historical pound sterling, used for financial transactions or endowments.

The term libra also had more specific historical variations:

• Libra arsa (meaning "burnt pound") referred to a historical practice where a pound of precious metal, such as silver, was melted down to verify its purity. This was a method to ensure the quality and true intrinsic value of the metal.
  Example: During a royal audit of the mint in 13th-century England, officials might perform a libra arsa on a sample of newly minted silver coins to confirm they met the required standard of fineness before being released into circulation.
  Explanation: This example shows how melting was used as a quality control measure for precious metals, ensuring their purity and thus their true value in coinage.
• Libra numerata (meaning "counted pound") referred to a pound of money that had been precisely counted. This method emphasized verification by enumeration, ensuring the exact quantity of coins was present.
  Example: When a feudal lord paid his annual taxes to the Crown, the royal treasurer might insist on receiving the payment as libra numerata, meticulously counting each coin to ensure the full pound sterling equivalent was delivered.
  Explanation: This illustrates the practice of counting individual coins to confirm the exact monetary value of a pound, preventing discrepancies and ensuring the correct number of coins was exchanged.
• Libra pensa (meaning "weighed pound") referred to a pound of money that was verified by weight rather than by counting. This method was often used to guard against coin clipping or debasement, where coins might be underweight even if the correct number were present.
  Example: To prevent fraud from clipped or worn coinage, a wealthy merchant receiving a large payment for goods might demand the sum be verified as libra pensa, placing the coins on a scale to ensure their collective weight matched the value of a full pound.
  Explanation: This example demonstrates how weighing coins was used to confirm their intrinsic value based on their precious metal content, especially when the integrity of individual coins might be compromised by wear or deliberate alteration.