How does one recognize the truth?
According to the Sages, there are several ways of doing so, and sometimes they have to be used in combination.
For example, there is the test of harmony; truth has to fit in harmoniously with reality.
Another test is that of eternity, the fact that a truth lasts and does not change.
Still another, far less philosophic, mark of truth is that it creates in one a click, an immediate responsiveness.
This "unthinking" recognition is not incompatible with the test of harmony.
–Rabbi Adin Steinsaltz
From In the Beginning by Rabbi Adin Steinsaltz