Elements of the past are mediated into the present by custodians, individuals in the present who decide which aspects of the past are nonessential to the tradition's future and, therefore, may be deleted or deemphasized. Custodians also decide which elements should be emphasized, highlighted, even added in order to ensure the tradition's survival in the future.
Tradition is dynamic, and it derives part of its dynamism from the transmission process. This transmission process is also subjective and shaped by the needs and assessments of people in the present. As Walter Benjamin put it, "every image of the past that is not recognized by the present as one of its own concerns threatens to disappear irretrievably.' Tradition is built on the past, and yet its relationship to the past is not natural but discursive, constituted by discontinuities as much as by its continuities. The analogy of a river changing its water captures the way the past operates in a tradition, as a 'continuity of adaptation,' both 'unlike the present and yet continuous with it.' 
 Grewal, Zareena. Islam Is a Foreign Country, 200.
 Grewal, Zareena. Islam Is a Foreign Country, 259.