Tranquillity is one of those words that actually looks simple at first, but they are not when you start looking at it very well. It sometimes stands for being quiet. Though it cuts across the philosophy of religion and life experiences, tranquillity is far deeper than the absence of noise.
The fact that everywhere is quiet does not translate to tranquillity. It is another form of discipline, a form of peace, a condition where the mind and the spirit is steady, even when the whole world is full of chaos and noise. In so many philosophical traditions, tranquility is synonymous to freedom, the ability to stay away from disturbance.
To be tranquil is to meet reality without exaggeration or resistance. In traditions and peace, peace is not supposed to be passive; it is cultivated through discipline and perspective. Religious traditions also treat tranquility as a profound spiritual state.
There are so many religions of this world and they have their own different interpretations of tranquility. Christians define tranquility as something that goes with surrender, divine peace and trust. They used to say it that it surpasses understanding.
The Islamic have their own definition which is similar but it values inward peace more, an absolute total submission to God and the ability to know where the heart becomes so settled and quiet in itself to be able to access things properly. Though all these traditions, tranquility has its own definition all across, but it still goes along deeper alignment between self and what is ultimate. There are things that make tranquility so compelling, modern life, reward speed, reaction, constant availability, but tranquility makes you see the best in yourself no matter how slow life might look.
There is also something deeply human about tranquil moments, most people can recall one, a light through the window might look quiet but it works, there is a hush after the rain and a conversation that needed no performance, a few minutes alone before the day began, that is a tranquil moment, a perfect moment to reassess and realign everything before it's done.