A Quote by David Bohm on thought, reflex, pattern, and system

Thought reflexes get conditioned very strongly, and they are very hard to change.  And the also interfere.  A reflex may connect to the endorphins and produce an impulse to hold that whole pattern forther.  In other words, it produces a defensive reflex.  Not merely is it stuck because it's chemically so well built up, but also there is a defensive reflex which defends against evidence which might weaken it.  Thus it all happens, one reflex after another after another.  It's just a vast system of reflexes.  And they form a 'structure' as they get more rigid.