The 4D Eigenvector 1 (E1) parameter space is an attempt to create an H-R Diagram for quasars. The E1 concept is briefly summarized as well as evidence that L/M ($\propto$ L/Ledd) is the principal physical driver of source occupation/correlation in E1. Recent E1 related tests and results are discussed including: 1) Identification of a class of extreme narrow line Seyfert 1 sources that show a blueshifted narrow line region providing a kinematic link between broad and narrow line gas in what may be the youngest AGN. 2) A quantitative attempt to decouple the effects of physics and source orientation in E1 using radio-loud AGN. 3) Discussion of the first hints about E1 source occupation at higher redshift using results of the first two years of our VLT-ISAAC campaign to follow the optical Balmer and FeII spectrum out to z~2.5. 4) Analysis of the E1 CIV shift parameter in an expanded sample of sources that supports the idea of two distinct AGN populations.