  After a short review of the quasar problem and what we can hope to learn from
their emission line spectra, I discuss the current body of knowledge concerning
quasar emission lines and their relationships to the local and ionizing
continua. I propose a hypothesis that the Baldwin effect is due to a
characteristic relationship between the continuum spectral energy distribution,
the gas metallicity (Z), and the quasar luminosity. I suggest that such a
relationship might arise naturally from a scenario involving massive galaxy
formation and evolution driving the birth and evolution of the quasar central
engines in terms of four fundamental parameters: M_bh, Mdot Mdot/M_bh, and Z.
