But as Geographers use to place Seas upon that place of the Globe which they know not: so chronologers, who are near of kin to them, use to blot out ages past, which they know not. They drown those Countries which they know not: These with cruel pen kill the times they heard not of, and deny which they know not.

Historical chronology, human or geological, depends... upon comparable impersonal principles. If one scribes with a stylus on a plate of wet clay two marks, the second crossing the first, another person on examining these marks can tell unambiguously which was made first and which second, because the latter event irreversibly disturbs its predecessor. In virtue of the fact that most of the rocks of the earth contain imprints of a succession of such irreversible events, an unambiguous working out of the chronological sequence of these events becomes possible.

History, if viewed as a repository for more than anecdote or chronology, could produce a decisive transformation in the image of science by which we are now possessed.