TRIAL AND ERROR
In hexagram structure there is a harmony between the third and sixth Lines. As the top Lines of their respective Trigrams, they embody completion principles. The third Line theme of Trial and Error is in harmony with the sixth Line theme of Wisdom. Only through trial and error can truth be experientially confirmed or not. The essence of being Human is evolving greater and greater efficiency.
Without the third Line capacity to discover flaws, to experience failure, each succeeding generation would have to start from the same point of inexperience and distrust. Sadly the third Line experienced as not-self leads to pessimism, distrust and a loss of self worth.