Although, for reasons already explained or surmised, the gravestones in our burial-grounds seldom exceed an age of 200 years, there has probably been no time and no race of men in which such memorials were unknown. Professor Dr. John Stuart, the Scottish antiquary,[15] opines that "the erection of stones to the memory of the dead has been common to all the world from the earliest times," and there are many instances recorded in the Old Testament, as when Rachel died and Jacob "set a pillar upon her grave" (Genesis, chapter xxxv. verse 20); and another authority, Mr. R. R. Brash,[16] in a similar strain, comments on the sentiment which appears to have been common to human nature in all ages, and among all conditions of mankind, namely a desire to leave after him something to perpetuate his memory, something more durable than his frail humanity. This propensity doubtless led him in his earliest and rudest state to set on end in the earth the rough and unhewn pillar stone which he found lying prostrate on the surface, and these hoar memorials exist in almost every country. [Footnote 15: "The Sculptured Stones of Scotland" (two volumes), by John Stuart, LL.D., Secretary to the Scottish Society of Antiquaries.] [Footnote 16: "Ogam Inscribed Monuments," by R.R. Brash; edited by G.M. Atkinson.] A remarkable instance is afforded by Absalom, the son of David, who himself set up a stone to record his memory: "Now Absalom in his lifetime had taken and reared up for himself a pillar, which is in the king's dale: for he said, I have no son to keep my name in remembrance: and he called the pillar after his own name: and it is called unto this day, Absalom's place" (2 Samuel, chapter xviii. verse 18). Professor Stuart indeed declares that there is no custom in the history of human progress which serves so much to connect the remote past with the present period as the erection of pillar stones. We meet with it, he says, in the infancy of history, and it is even yet, in some shape or other, the means by which man hopes to hand down his memory to the future. The sculptured tombs of early nations often furnish the only key to their modes of life; and their memorial stones, if they may not in all cases be classed with sepulchral records, must yet be considered as remains of the same early period when the rock was the only book in which an author could convey his thoughts, and when history was to be handed down by memorials which should always meet the eye and prompt the question, "What mean ye by these stones?"