Have you ever made a todo list? Lists in general are a useful tool for dealing with a linear thought process. Lists that are composed of lists can be used to generate hierarchies, which are also a very useful tool for dealing with a hierarchical thought process; for example, a plan that consists of multiple steps that are each composed of substeps. I like to write computer programs that generate my todo lists. I tell the computer the important data to consider (such as the list of graduate schools to apply to with application due dates). With a little coercing, the computer will give me a sorted list of graduate schools to apply to (all of them happened to be due on December 15th so this program didn't actually do much in practice). I consider this to be programming my mental thought process. It would be interesting to see if programming interfaces could become so efficient and easy to use and learn that we all use this method of planning our large decisions (such as life plans). What keeps life exciting? The people at the center of this system. Government regulation of the types of processing that can be done within a person's own mind will become serious societal concerns if we don't think about these issues incrementally: privacy, security, and freedom for the individual.