Sprezzatura, the Skill of Humility.

Practice in everything a certain nonchalance that shall conceal design and show that what is done and said is done without effort and almost without thought.
Baldassare Castiglione
Have you ever dealt with people who will constantly remind you just how difficult their work is? Do they work from crisis to crisis? How does that attitude affect those around them? Very few things are as distressing as having, not only to deal with the project at hand, but with the constant stress of dealing with the person on the edge of a nervous breakdown or constantly bragging about how indispensable their skill and how much better than you they are. Yet we live in a culture that discourages and is suspicious of discretion and restraint.
The ultimate paradox is how we applaud those who show careless mastery of a skill, give a sense of confidence to those around them, who can reassure even the unbelievers with a quick smile and a “I got this shit.”

And that, Gentlemen, is called Sprezzatura

Sprezzatura is that confidence exuded while doing things as a second nature, that ineffectual natural calmness. The confidence, the natural calmness? There lies the hardest part. The reality is these are to calm those around us. We might be just as worried, just as stressed, just as nervous; but our role is to provide that confidence and comfort in those around us. 

We, as Gentlemen, must develop an attitude of discretion, restraint, and, as a result, humility. This restraint, and the etiquette supporting it, is to give us a chance to negotiate slowly and carefully how to handle a situation. The ability to pause before acting and then to act sensibly is a developable skill.
A man who has Sprezzatura is content with himself. He doesn’t need to justify his actions. More so, he might even prefer they not be understood. His actions, including his carefully chosen words, speak for him. 

Suddenly humility and discretion become power. People trust you because you ARE trustworthy. It may call upon every bit of your strength to restrain yourself from saying or doing more than you should, for you might run dangerously close to arrogance and insecurity. It is Sprezzatura a combination of an effortless elegance but also a strenuous self-control. It defines a man’s power: the stronger and wiser he is, the gentler his manner. And it is the difference between being a Gentleman and a man doing “gentlemanly things.”