On the eve of the LHC: conceptual questions in high-energy physics

We start by remarks on the scientific and societal context of today's theoretical physics. Major classes of models for physics to be explored at the LHC are then reviewed. This leads us to propose an LHC timeline and a list of potential effects on theoretical physics and the society. We then explore three conceptual questions connected with the LHC physics: symmetry (and symmetry breaking), effective field theory, and fine tuning.