"An ego thus educated has become reasonable; it no longer lets itself be governed by the pleasure principle, but obeys the reality principle, which also at bottom seeks to obtain pleasure, but pleasure which is assured through taking account of reality, even though it is pleasure postponed and diminished." Sigmund Freud
Lady Macbeth:
Why did you bring these daggers from the place?
They must lie there. Go carry them, and smear
The sleepy grooms with blood.
Macbeth:
I'll go no more.
I am afraid to think what I have done;
Look on't again I dare not.
Lady Macbeth:
Infirm of purpose!
Give me the daggers. The sleeping and the dead
Are but as pictures; 'tis the eye of childhood
That fears a painted devil.
Macbeth Act 2, scene 2, 45–52