  Some of the principal heliophysical inferences that have been drawn from, or
refined by, seismology, and the manner in which those inferences have been
made, are very briefly described. Prominence is given to the use of simple
formulae, derived either from simple toy models or from asymptotic
approximations to more realistic situations, for tailoring procedures to be
used for analysing observations in such a way as to answer specific questions
about physics. It is emphasized that precision is not accuracy, and that
confusing the two can be quite misleading.

Solar and Stellar Astrophysics