When your mind is calm and clear in stillness, wisdom and inner truth arises.
Wisdom derives from being able to look honestly in your heart without emotion. As then truth arises where you see things as they are. There is no sense of ego attachment to fear, anger, pain or grasping so you can look at things clearly.
It requires a full presence of moment to moment awareness by consistently looking inward and contemplation.
You will know where you are; from how you interact with others and respond to situations in your daily life. This will give you a clue to your inner truth.