We are actually learning to shed the sophistication of our intellect and the accumulation of mental possessions. We are learning to go back to the simplicity of our childhood, and to our original nature which was so pure and untainted. That is why many sages are esteemed for a childlike quality in their nature. This does not mean the wise man has reverted to childhood. A child is innocent but lacks the maturity and the wisdom to handle his own life.
Adults have the maturity to some extent, but lack the innocence.