Thus, from very early if not from pre-historic times, down to the present moment there have been repeated if not continuous examples, and widespread on the earth if not universal, of the place and importance of oral tradition as a datum of history and source of literature. Says Professor Sayce: "Archæological research is constantly demonstrating how dangerous it is to question or deny the veracity of tradition or of an ancient record until we know all the facts."[12] This much must be conceded, in holding that oral tradition is secondary to written records. The reason for their secondary value is obvious from the fact that "ear impressions tend to be less exact than eye impressions because they depend on a brief sense impression, while in reading the eye lingers until the matter is understood. Memory copy tends to fade away rapidly. This is shown by the great variety in the related legends of closely related tribes."[13] But from very early times--just how early cannot be determined, inasmuch as historiographers and chronologists differ as to the beginning-times of written literature in the respective civilizations--literary compositions of every sort, both sacred and profane, were recorded and disseminated, so far as they were recorded and disseminated, by the tedious and laborious process of writing or carving or impressing by hand. Literature, almost entirely, throughout this long period was contained in and continued by the manuscripts. The cuneiform writing on tablets and cylinders, though so voluminous in quantity, seems to have been lost sight of and disregarded for millenniums of years while they were a sealed literature; and the hieroglyphic writing of Egypt remained undeciphered for, perhaps, an equal period of time, down to the close of the eighteenth century.