Sometimes, I guess, an over-valent idea enters the mind as a problem, or imaginary problem. This is not so rare. You are getting ready for bed, late at night, and all of a sudden the idea comes into your mind that you did not shut off your car lights. You look out the window at your car-which is parked in your driveway in plain sight-and you can see that it shows no lights. But then you think: Maybe I left the lights on and they stayed on so long that they ran the battery down. So to be sure, I must go out and check. You put on your robe and go out, unlock the car door, get in and pull on the headlight switch. The lights come on. You turn them off, get out, lock up the car and return to the house. What has happened is that you have gone crazy; you have become psychotic. Because you have discounted the testimony of your senses; you could see out the window that the car lights were not on, yet you went out to check anyhow. This is the cardinal factor: you saw but you did not believe. Or, conversely, you did not see something but you believed it anyhow. Theoretically, you could travel between your bedroom and the car forever, trapped in an eternal closed loop of unlocking the car, trying the light switch, returning to the house-in this regard you herewith are a machine. You are no longer human.