l u c i d i t y

lucidity

  (loo-sid-i-tee)

noun 

1.  characterized by clear perception or understanding; rational, sane, comprehensible:
     "a lucid moment in her madness."

2.  a capacity to perceive the truth directly and instantanously; clairvoyance.  

3.  shining or bright.  

from the latin lucidus meaning "light, bright, clear."