A more thorough explanation:

Definition: Four corners refer to the face of a written instrument, such as a contract. It is a legal term that comes from the ancient practice of putting all instruments on a single sheet of parchment, no matter how long the sheet might be. This practice prevented people from fraudulently inserting materials into a fully signed agreement. The requirement was that every contract could have only four corners.

Example: When signing a lease agreement, it is important to read and understand all the terms and conditions written within the four corners of the document. This means that any additional clauses or agreements outside of the four corners are not legally binding.

Explanation: The example illustrates how the term "four corners" is used in legal documents. It emphasizes the importance of reading and understanding all the terms and conditions within the four corners of a contract. This ensures that both parties are aware of the agreement's contents and that no fraudulent materials are inserted outside of the four corners.