The main aim of conservation is the preservation of our cultural heritage for future generations. Today, conservation is generally defined as the ‘management of change'. This definition recognises that all buildings and artworks change over time, whether by means of natural physical change, such as the building-up of a patina, or by deliberate action, such as additions, repair or damage. In many cases in the past, conservators attempted to recreate the original state, often by means of removing significant historical accretions. Today, such alterations are often recognised as being valuable in their own right and as evidence of the object's past history and usage.