'Philosopy bites' is a fantastic set of podcasts which provides accessible but top end contributions from leading philosophers on a variety of subjects. I listened again recently to one on the role and development of the imagination and how it helps us to understand and appreciate causal relationships http://philosophybites.com/2011/06/alison-gopnik-on-the-imagination.html
In evolutionary terms, the very extended and protected period of childhood allows exploration through the imagination without the responsiblities associated with survival so that once adult the individual can apply the product from this learning to get things done. The podcast rather facetiously suggests that children are the 'R&D division' and adults the 'production and marketing division' of human beings plc. The insight that not having to focus on short term goals allows us to be able to accomplish goals in the longer term is increasingly well appreciated in spheres such as think tanks, strategy units and firms in silicon valley which all pride themselves on innovation and where efforts are made to capture (through the use of play rooms and play things) some of the child like exploration from which our ability to think differently arises. But it also reinforces that a constrained and regimented approach to child development particularly through the education system is short sighted and in fact counter to our basic evolution!
There is then some discussion about philosophy as 'theoretical everything' i.e. there is always a more abstract and theoretical end of any spectrum (so for example ethics might be seen as the very theoretical end of law; aesthetics as the theoretical end of art). Importantly, these are points on a spectrum or different parts of a web; not different worlds. Perhaps a statement of the blindingly obvious. But an under appreciated one.
Imagination developed as an evolutionary tool to help us to think about cause and relationship. The abstract tells us a huge amount about the concrete. It was meant to do so. Recognising that there is a 'theoretical' in everything at a time when the emphasis is on the supposedly practical is worth well worth remembering.