Much progress has been made in the last 50 years in our understanding of bone's mechanical properties, and the reasons it has these properties and not others. The question is to what extent these advances have arisen from an increase in the techniques available for the study of bone, and how much stems from an increased understanding of the basic processes involved. Although considerable enlightenment has come from the transfer of ideas from the physical sciences, in particular materials science, the author argues that most increases have come from the vastly increased power and resolution of the observational and mechanical techniques available. Even so, the remarkably hierarchical nature of bone's structure makes it an almost uniquely difficult material to understand properly, and much remains to be done to marry explanations at the macro-, micro- and nanolevels to obtain a full understanding of bone mechanics.