There has been much progress in the task of caring for our cultural heritage over the last 50 years: The fields of preservation and conservation have become organized and professionalized. While the term 'conservation' includes activities relating to both prevention and remediation of decay, in this paper the term 'preservation is used exclusively to describe efforts to prevent or slow down the deterioration of cultural property. There are journals, conferences like this one, research laboratories and an active marketplace of special materials and technology for housing and storage of cultural objects. However, one of the challenges that has been present for a very long time is the tension between preventing deterioration before it occurs and restoring objects that have already deteriorated. Which is more important? Clearly both these activities make perfect sense to do, but what should the balance be between them? It seems that the preservation and conservation fields have not yet provided museums with a unified vision or specific advice on how to strike that balance, either in general terms or in particular circumstances. The amount of time, effort and money devoted to what is sometimes called 'preventive conservation' remains controversial.