are you here? / I've been sleepwalking again, my dear. / The plants are moving under the rug.

Resedenduft durchs kranke Fenster irrt.
Ein alter Platz, Kastanien schwarz und wüst.

If you see me leave the house in the morning and you know that my wife gives me either 2 or 10 dollars for the day (with equal probability), the expectation value of the money in my pocket is 6 dollars.
If you now see me spend 3 dollars, then the expectation value of the money in my pocket is 7 dollars.

Think about it and think about quantum mechanics.