It is the beginning of the Bene Geserit "Litany of Fear" in Hebert's book, "Dune".
When in a complete state of fear it is impossible to think rationally. Our reptillian (old brain) takes control over our human (new brain) in that state. We must master our emotions and separate our instinct from rational thought in order to allow rational thought to prevail in what otherwise might be overwhelming situations.
"If you can keep your head when all about you are losing theirs, then you shall be a man (huMAN) my son." Rudyard Kipling
It's reality it's not a new idea.
"Fear is the mind-killer" Muad'Dib Me 53, XW 44, DD 14, DS 12 Bomb and OM 12/15/06 Separated 01/02/07 Divorced 05/13/08 X married OM(OMH) 08/2009 Married 06/09/13