The concept of reflection is fundamental to Kant and Hegel’s view of reason, and on a very down-to-earth level to supporting what I call emotional reasonableness.
Reflection occurs through the medium of discursive development. What we experience as immediate consciousness is the result of pre-conscious syntheses of imagination that in part build on past knowledge and experience in accordance with our dispositions and character, but in part simply represent shortcuts (assumptions and pre-judgments) that enable us to respond rapidly in situations where there is no time for prolonged reflection.
Neither Plato nor Aristotle has a Greek word that exactly corresponds to reflection in Kant and Hegel’s sense, but a similar concept permeates their work. Platonic dialogue is implicitly reflection that is shared between two or more persons. Aristotelian deliberation, contemplation, and normative saying are all implicitly grounded in reflection. Our higher destiny as talking animals is to reflect. What we reflect on includes deeds and motivations in general, not only the special kind of deeds that are sayings. It also includes relevant circumstances.
In recent times, Paul Ricoeur and Robert Pippin have each made important uses of the concept of reflection.
The Postmodern Peripatetic 