Via Lifehacker, a nice little essay on "the chokehold of calendars," and how we've accidentally (or thoughtlessly) designed them to kill our productivity and concentration:

The idea of a calendar as a public fire hydrant for colleagues to mark is ludicrous. The time displayed on your calendar belongs to you, not to them….

The problem with calendars is that they are additive rather than subtractive. They approach your time as something to add to rather than subtract from. Adding a meeting is innocuous. You’re acting on a calendar. A calendar isn’t a person. It isn’t even a thing. It’s an abstraction. But subtracting an hour from the life of another human being isn’t to be taken lightly. It’s almost violent. It’s certainly invasive. Shared calendars are vessels you fill by taking things away from other people.

"I’m adding a meeting" should really be "I’m subtracting an hour from your life."

Amen to that….