After the death of David Laing, his private library was sold in an auction occupying thirty-one days. His collection of charters and other papers is of national importance and the most distinguished of its kind in any Scottish university. It is an essential source for the 18th century, and a much used one for all periods of Scottish history from the earliest times. The Laing Collection falls into five sections, designated as La.I., La.II., La.III., La.IV., and La.V.