Royal Australasian Ornithologists Union early 20th century called themselves 'oologists', though the distinction between the notionally scientific discipline of oology and simple egg-collecting was blurred. Identification of any but the most common and distinctive species usually entailed the collection of specimens to be made into study skins. Modern field-guides did not exist and few people could afford the massive multi-volume, lavishly illustrated, handbooks of John Gould and Gregory Mathews. However, both Archibald J. Campbell and Alfred North had produced comprehensive guides to what was known about the nests and eggs of Australian birds, with illustrations of the eggs rather than of the birds themselves,
What Is History? that historians deem unimportant, and "historical facts", information that the historians have decided is important. Carr contended that historians arbitrarily determine which of the "facts of the past" to turn into "historical facts" according to their own biases and agendas. For this reason, Carr argued that Leopold von Ranke's famous dictum "wie es eigentlich gewesen" (show what actually happened) was wrong because it presumed that the "facts" influenced what the historian wrote, rather than the historian choosing what "facts of the past" he or she intended to turn into "historical facts". At the same time, Carr argued that the study