A quality which ought to form a part is easily presumed.

Explanation

(English-origin maxim.) Where a quality naturally belongs to a thing or transaction, the law readily presumes its presence without requiring separate proof — what ordinarily accompanies a thing is presumed to be part of it.

Where this applies

• A man dies owning a house — the court presumes he also held the keys, the furnishings inside, and the right to rental income, because those things naturally accompany home ownership.
• A valid contract is presented — the court presumes the parties had the legal capacity to enter it, because capacity is a quality that ordinarily accompanies a contract signing.
• A public official takes office — the court presumes he took the required oath, because oath-taking is a quality that naturally forms part of assuming public office.