What is the difference between tact and politeness?

Francois Truffaut lets Delphine Seyrig tell Jean-Pierre Leaud in a letter in the film Baisers Voles (Stolen Kisses).  Baisers Voles, the original French title of the film comes from a line in Charles Trenet's song "Que reste-t-il de nos amours?", known in English as "I Wish You Love."

"One of my teachers once explained the difference between tact and politeness.  A man opens a bathroom door by mistake and sees a naked lady.  He steps back and says "Excuse me madam."  That's politeness.  The same man finds the same naked lady and says "Excuse me sir."  That's tact.

Amazon carries Stolen Kisses.

Childhood is not just preparation for “real life,” it’s a good portion of life itself.

This is an excerpt from Christina Schwarz's article in the April 2011 issue of The Atlantic --- Leave Those Kids Alone - Childhood is more than merely a springboard to adulthood.

But childhood is not just preparation for “real life,” it’s a good portion of life itself. If the golden years of childhood are from age 3 to 12, they encompass more than twice the time people spend in what is generally regarded as a focal point of life: the college years. As Smith’s memoir demonstrates, childhood—those first, fresh experiences of the world, unclouded by reason and practicality, when you are the center of existence and anything might happen—should be regarded less as a springboard to striving adulthood than as a well of rich individual perception and experience to which you can return for sustenance throughout life, whether you rise in the world or not. Children have a knack for simply living that adults can never regain. If they’re allowed to exercise it a bit, perhaps they’ll have childhoods, like Smith’s, worth remembering. 

It is all absurd when one thinks about death. Everything is interchangeable.

From My Prizes: An Accounting, by Thomas Bernhard.

“There is nothing to praise, nothing to damn, nothing to accuse, but much that is absurd, indeed it is all absurd when one thinks about death. We go through life impressed, unimpressed, we cross the scene, everything is interchangeable, we have been schooled more or less effectively in a state where everything is mere props:  but it is all in error! We understand:  a clueless people, a beautiful country --- there are dead fathers or fathers conscientiously without conscience, straightforwardly despicable in the raw basics of their needs...it all makes for a past history that is philosophically significant and unendurable."