Extracting accurate and precise physical information from stellar spectra is a century-old effort. These spectra are known to contain the information to determine masses, ages, luminosities, velocities and element composition of stars: quantities that form the foundation for a host of astrophysical studies; but it is hard to get this information out.

I will lay out new ways to read physical quantities from stellar spectra that boost not only measurement precision, but also allow new kinds of quantities to be inferred.

I will show what this is now teaching us about the formation history of our own Galaxy, when combined with the ultra-precise position measurements of the Gaia space mission: what processes set the overall radial profile of the Milky Way's disk, or the present-day orbital of any star? And how much formation memory does the Milky Way's disk retain?