Few manuscript collections contain thorough documentation of all phases of the subject's life, especially of those important phases during which his impact was most clearly evident. Even those periods of a donor's life that appear best documented will usually be found wanting; the documents seldom adequately reflect the considerations that contributed to key decisions and very rarely betray the donor's candid opinion of events and people with whom he interacted. Collections of personal papers are especially weak in the information they provide on the formative years of their donors—years that often hold the keys to perceptions that influenced their subsequent actions. Even correspondence does not always betray the author's inner thoughts, and it may, depending upon the intent behind it, be quite misleading to the researcher.
In these and related instances oral history seems a necessity rather than the luxury it often appears to be. Without properly conducted interviews, the papers of a politician or businessman may lack highly significant perspectives that do not appear on paper. Oral history interviews can document current events in a manner that traditional archival collecting cannot. Interviews can most definitely help deal with the modern paper mountain and its paucity of hard data.