"Mad as a hatter" is a colloquial English phrase used in conversation to suggest (lightheartedly) that a person is suffering from insanity. The etymology of the phrase is uncertain, with explanations both connected and unconnected to the trade of hat-making.
Note: In the 19th century "hatters" or hatmakers used nitrate to treat their fabrics. This is a poisonous substance, and if the hatmakers breathed it in, they often suffered brain damage. As a result, hatters were traditionally thought of as mad.
Here are a few "mad" examples of very daring hats worn at Royal Ascot throughout the years.
