Short idea (113): From a developmental point of view, I think that Sensation must have been the first adaptive psychological function to appear (every living cell senses — as do human infants). Imagination assumes Sensation and builds on it, and I think it must have been the second function to appear (dogs dream). Thinking assumes Imagination and Sensation and integrates them into itself, and, I think, it must have been the third of the functions to appear (language is needed for thinking; infants don't yet have language). Reflection, Evaluating, Moral and Ethical Reflection, and Planning integrate Sensation, Imagination, and Thinking, and I think it is the fourth function to arise and probably does not arise in everyone. Wisdom couldn't develop without being able to build on the previous four functions and there would also have to be character traits present such as courage. And, if there is any psychological function further along than Wisdom, perhaps some Unifying function, it would develop, if at all, only after everything else was in place and functioning.