One theme is a scrutiny of the history of ideas for the first points at which distinctions between forms of thought were first articulated, and then the point at which they became recognized, and then the point at which they began to be reflected upon. It seems to only make sense to reflect on the history of philosophical attempts to construct some kind of map of thought in the light of what is now actually known about both how culture has developed and about our actual biological functioning.
Interestingly, a pluralistic understanding of forms of thought, which seems to be the most defensible philosophical account, is now being paralleled by developments in scientific disciplines. Since monism has been the Platonic and Christian norm for around two and a half millennia, this may turn out to be a seismic cultural shift of what I think would in general be a very positive sort.
The knowledge supplied by archaeology, anthropology, cognitive psychology, and neuroscience about early humans and about how the brain and mind work can't be ignored by anyone interested in theories of modality. Such theories are basically classifications or sets, dealing with a very peculiar object, conscious experience.
It helps then to know what one has in mind by a set or classification; and it seems that we begin to classify the world long before we know that that is what we are doing, long before we explicitly try to do so, and even longer still before we start to reflect philosophically on the fact that this is what we are doing.
Without committing the genetic fallacy of making origins the most important thing, it is nevertheless vital to have some notion of how the different departments of thought first arose in the ancient world that is as empirically grounded as may be in order that one may be able to answer the question of what changed afterwards. What is needed is a work not of speculation but of synthesis.