On the Interpretation of Quantum Theory - from Copenhagen to the Present Day

A central feature in the Copenhagen interpretation is the use of classical concepts from the outset. Modern developments show, however, that the emergence of classical properties can be understood within the framework of quantum theory itself, through the process of decoherence. This fact becomes most crucial for the interpretability of quantum cosmology - the application of quantum theory to the Universe as a whole. I briefly review these developments and emphasize the importance of an unbiased attitude on the interpretational side for future progress in physics.