From the writings of 20th-century liturgical essayist Msgr. Romano Guardini (1885-1968):
Composure is more than freedom from scattered impressions and occupations. It is something positive; it is life in its full depth and power. Left to itself, life will always turn outward toward the multiplicity of things and events, and this natural inclination must be counterbalanced. Consider, for a moment, the nature of respiration. It has two directions: outward and inward. Both are vital; each is part of this elementary function of life; neither is all of it. A living organism that only exhaled or only inhaled would soon suffocate. Composure is the spiritual man’s “inhalation,” by which, from deep within, he collects his scattered self and returns to his center.
Only the composed person is really someone. Only he can be seriously addressed as one capable of replying. Only he is genuinely affected by what life brings him, for he alone is awake, aware. And he is not only wide awake in the superficial sense of being quick to see and grab his advantage — this is a watchfulness shared also by birds and ants. What we mean is true awareness: that inner knowledge of the essential; that ability to make responsible decisions; sensitivity, readiness, and joy.
Once composure has been established, the Liturgy is possible.
Not before. It is not much use to discuss Holy Scripture, the deep significance of symbols, and the vitality of the liturgical renewal if the prerequisite of earnestness is lacking. Without it, even the Liturgy deteriorates to something “interesting,” a passing vogue. To participate in the Liturgy seriously we must be mentally composed. But, like silence, composure does not create itself; it must be willed and practiced.
— Meditations Before Mass (1939)