If one has no though left (you can call it an empty mind) which is from the 'old' Zen masters basically the flipside.. Complete Zen is death in our words and a Zen mind, or the study into Zen. Tao tse etc.. had some Masters who thought it was a good idea to withdrawn 'the knowledge of the perhaps deeper and so, darker side of its study', from society.
Also Goethe's Faust: a book which describes the negative side of knowledge...
Very good question :)
shahzar_ali_khan