In the previous section it was discussed how families screen off
certain emotions, and that unconscious attractions works on the
principle that we tend to pick partners that have the same emotions
screened off and hidden, even to themselves. In this section Robin
and John talk about the screen and how it sometimes slips to let out
repressed and 'taboo' emotions.

John: In what way does the screen not work?

Robin: In several ways. First, it slips up now and again, and lets the
forbidden feelings out for a bit. Second, trying to keep the screen
firmly in place takes up a lot of energy. And third, well, you can't
just cut off a bit of human personality without unbalancing the whole
system - the whole human being.

John: Very glib, Doctor. Could we take them one at a time, please? The
screen can slip?

Robin: Yes, especially if we're tired or ill or have a bit too much lo
drink. Then the emotion can escape. And because we're out of touch
with it, it takes us by surprise and isn't easily controlled if it
does. So we might suddenly say or do something very nasty, something
that seems 'not like us'.