In contrast to modern psychologists, ancient scholars explored human nature primarily through:

The answer is insights inferred from anecdotes. A manuscript about human nature is revealed and scientist approve that it is the work of an ancient scholar. This manuscript is more likely to explore human nature through insights inferred from anecdotes. Modern psychologists rely heavily on empirical evidence, whereas some of the great thinkers of history depend on more on observations based on anecdotes or on descriptions of a few individuals.

They went to leyden, holland