Physics and astronomy are the oldest sciences and the concept of mass is thus a very old concept. We have quite good understanding of the masses of composite elementary particles such as protons using quantum chromodynamics. But we do not understand the nature of the masses of the elementary particles - quarks, leptons, force carrying particles, dark matter particles - and we have no quantitative rules for the magnitude of their masses. In this talk I sketch a number of qualitative questions such as why is there no rule for even the simplest mass sequences - the charged leptons, is there a maximum mass elementary particle, and is the Planck mass idea overrated? I also estimate the upper limits on collider searches in the next few decades for massive particles. This is a summary of my talk at Colliders to Cosmic Rays 2007.