Like every other form of knowledge, science is grounded in tradition. The working man of science occupies himself with the knowledge that is handed down to him by his predecessors as surely as the lawyer or theologian. And if the body of scientific knowledge changes and develops more rapidly than legal or religious codes, that is but an added reason for learning something of the conditions of its change and development. This can be done only through history. Science is an organic product, and, like other results of living activity, its true nature can be discerned only in an evolutionary context. Past and present are indissolubly one.