What method did Galen use to diagnose patients?

Galen primarily used a combination of clinical observation and the examination of symptoms to diagnose patients. He emphasized the importance of observing the patient's overall condition, including physical signs and behaviors, while also considering their medical history. Additionally, Galen employed the theory of the four humors—blood, phlegm, black bile, and yellow bile—to interpret imbalances that could lead to illness. His approach laid the groundwork for future medical diagnostics by integrating empirical observation with theoretical understanding.