We are inveterate commemorators, whether concerning our private lives or the common history of humanity. Especially when there looms upon the horizon a round-number anniversary of an outstanding political or religious figure, a poet or musician, a scientist or philosopher, we feel summoned to make some special response of celebration and interpretation. The quality of such a commemorative response is not measured by its lavish appearance, but rather by the range and perceptiveness of the effort to rethink a great man's accomplishments and his facets of significance for ourselves. The more we penetrate into his work and vision, taken in their own form as well as their shaping impact upon subsequent history, the more we enrich our sense of human resources to draw upon in meeting the problems of present existence. A commemoration signifies both that the source in question has an unsuspected fecundity, still to be realized, and that its realization comes about in the course of our active wrestling with issues rather than in the artificial calm of pure recall.