The loss of musical material from Bach's death to the first printings of chorale collections may have been substantial. Not only are many works the chorales were extracted from no longer extant but there is no way of knowing how much of all the harmonisations that were once compiled the current collections include. For example, there is no way of knowing how many of the 150 harmonisations first proposed for sale in 1764 also appear in Princess Anna Amalia's manuscript which ultimately forms the basis of the Breitkopf edition. As to the chorale melodies with figured bass, current collections include less than one hundred of them whereas those proposed for sale in 1764 numbered 240.