There are three sources of Truth: rationalism, empiricism, and faith. Throughout much of history, faith dominated, though without proper knowledge, faith can lead to wrong conclusions just as surely as the other two can when exercised without balance.
With the Enlightenment, Reason became the most sought after source of Truth, and with Modernism it became Empiricism (in the form of Science). This was later replaced by feelings and emotion in the Post Modern movement.