Self-knowledge or Self-discipline

Is tranquility of mind achieved through self-knowledge or self-discipline - with practice? 

I believe that both are required to achieve it. 

Knowledge of the object and the goal is essential, but one needs to practice the art and skills to achieve it. 

Self-knowledge is undoubtedly the most significant and crucial part - but still, we need to practice it with self-discipline to make it a part of our nature to achieve continual tranquility. 

Just as a clear and bright image appears not in disturbed, but only in still waters - 

Only a tranquil - calm, and silent mind can come in contact with Reality. 

Gyan and Karma - Knowledge and Action - are compared with two wings in the ancient scriptures.
A bird needs to have both wings equally strong to be able to fly high.
                                                                 ' Rajan Sachdeva '