“You are not your user”
A reminder that you are not designing the product for people like yourself. Often used as a way to encourage more user research in a project.

“If Henry Ford had asked people what they wanted, they would have told him faster horses”
Used as a counterargument to the previous statement, when you start to realize you won’t have time or money to do enough user research.

“People don’t want to buy a quarter-inch drill bit; they want a quarter-​inch hole”
Wait, do they really want a hole? Or do they want wireless Bluetooth instead, so no holes are needed whatsoever?

If you can’t convince them, confuse them.

“If you think good design is expensive, you should look at the cost of bad design”