Our understanding of microbial cellulase systems has evolved tremendously since the black-box “C1-Cx” theory of Drs. Elwyn Reese and Mary Mandels. The phenotypic observations and experimental results of countless studies in past 30 years can assist in the rationale design and interpretation of experiments using the tools of modern biology, its “ohmic” approaches, mutlivariant analyses, high throughput screening and bioinformatics. This presentation will provide a perspective of the past in the context of today and tomorrow, toward fully realizing cellulase-cellulose bioconversion in simultaneous-saccharification fermentation (SSF) systems. This presentation is dedicated to the life and memory of Dr. Raphael Katzen.