"truly I tell you, unless you change and become as little children you will in no way enter into the Kingdom of Heaven."
"Until you make the unconsciousness conscious, it will direct your life and you will call it fate." Carl Jung
So what is being talked about here, well from Jesus He is clearly saying that you must return to being a little child to have ANY hope of entering absolute peace and perfection.
What does that mean?
When we were small (little) children we were both unconscious (absolutely as a baby and semi-conscious as an infant) and semi-conscious as we were raised (retarded) by our parents, they following the defective world model for imprinting children into society.
Jesus is not telling us to become, or return to acting like children; He is telling us to search within to rediscover our unconscious spirit mind/self by focusing internally mentally and invalidating our outward conditioning. Just compare pictures of yourself as a baby and those of you as a fully conscious child; two different yet connected beings.
Jung, who after practicing psychiatry for many years changed to a more spiritual way of looking at mental illness and charged us to follow Jesus' instruction by changing the word children to consciousness. The term "little children," becomes unconscious spiritual and adults being worldly conditioned consciousness.