Louis Menand, in his introduction of To The Finland Station:
When you undertake historical research…your knowledge of the past—apart, occasionally, from a limited visual record and the odd unreliable survivor—comes entirely from written documents. You are almost completely cut off, by a wall of print, from the life you have set out to represent. You can’t observe historical events; you can’t question historical actors; you can’t even know most of what has not been written about. What has been written about therefore takes on an importance which may be spurious. A few lines in a memoir, a snatch of recorded conversation, a letter fortuitously preserved, an event noted in a diary: all become luminous with significance—even though these are just the bits that have floated to the surface. The historian clings to them, while somewhere below, the huge submerged wreck of the past sinks silently out of sight.