"Los prejuicios son lo que los tontos usan para razonar."

Simplified Meaning:

When people don't understand something or someone, they might quickly judge it based on their own wrong ideas or biases instead of thinking carefully. This behavior often shows a lack of real understanding or intelligence. For example, if someone meets a person from a different culture and immediately thinks something negative about them without getting to know them, they are using prejudice instead of reason. This is like a person deciding that all dogs are dangerous because they saw one dog growl. They aren't using their brain to think clearly; they are just jumping to conclusions based on little information. To live better and make fair decisions, people need to try to understand others and not let their first negative thoughts guide them. By being open-minded and curious, they can learn more and make wiser choices.