Discretion and Transparency

Lately I've been thinking about discretion. It's the strangest of virtues: you're only aware of it when one is indiscrete. Should someone talk of another behind their back, we assume that this someone will cross us, too. There must be a word for this category, where you're only aware of it when it is violated. Trust is like this too, and I guess it's appropriate that trust and discretion tend to…