But at the level of the capability hierarchy where we wish to work, it seems useful to us to distinguish several different types of structuring--even though each type is fundamentally a structuring of the basic physical processes. Tentatively we have isolated five such types--although we are not sure how many we shall ultimately want to use in considering the problem of augmenting the human intellect, nor how we might divide and subdivide these different manifestations of physical-process structuring. We use the terms "mental structuring", "concept structuring", "symbol structuring", "process structuring," and "physical structuring."