Tranquility Can Be Trained

Comments from the classical commentaries: 


Peace is the characteristic of the Tranquillity Link to Awakening (Passaddhi-sambojjhanga). Stilling of all bodily activity, feeling, perception, mental construction and consciousness is the purpose of tranquillity. Settled, serene and solidified calm (samatha) 
is the excessively pleasant manifestation of tranquillity. A smiling mountain!
When the mirror moves & vibrates, then one cannot see anything clearly in it. So also with the mind: When stressed and agitated, then mind cannot figure out what is good and what is bad on the long term. But when imperturbably stilled, then mind can cut right through any distraction and attain absolute  certainty and understanding both spontaneously and instantaneously...

Further conditions helpful for the emergence of the Tranquillity are:
1: Eating good and fine food...
2: Living in a pleasant climate...
3: Maintaining a comfortable posture without pain or distress...
4: Staying evenly ballanced in all situations and regarding all aspects...
5: Avoidance of restless, anxious, agitated, worried and stressed people...
6: Friendship with bodily and mentally calm people, who meditates much!
7: Commitment to calm down the mind by cultivating quiet and tranquillity!

-An excerpt from Bikkhu Samahita's Daily Damma Drops