In his much quoted critique of medieval historiography, R.J. Collingwood noted that historians,
… in their anxiety to detect the general plan of history, and their belief that this plan was God’s and not man’s, they tended to look for the essence of history outside history itself, by looking away from man’s actions in order to detect the plan of God; and consequently the actual detail of human actions became for them relatively unimportant, and they neglected that prime duty of the historian, a willingness to bestow infinite pains on discovering what actually happened.*
Set aside for now the more or less obvious irony of selectively pulling eminent quotes on historiography without reference to their own historiographical context. I want to highlight it here for the way that it frames the forensic basis of what historians do. “Telling it like it was” or “showing it the way that it happened” (wie es eigentlich gewesen ist) is a standard refrain of modern historical practice (as a professionalised research discipline). The work is oriented toward sources: who and what those sources are; the information they convey about people, places and events; and their credibility as conveyers of information (and by extension, the credibility of the information they convey).
*R.J. Collingwood, The Idea of History: With Lectures, 1926-1928 Rev. Ed. (Oxford and New York: Oxford University Press, 1994), p. 55. Originally published in 1944, after Collingwood’s death.