Laudator Temporis Acti

Ronald Syme, "Fictional History Old and New: Hadrian," in his Roman Papers, VI (Oxford: Clarendon Press, 1991), pp. 157-181 (at 158):

The historical novel may be described as legitimate and harmless. The intent is to convey entertainment in the first place, although not always avoiding instruction in social or political doctrines; and the author can seldom dissemble his own milieu and opinions.

By contrast, fictional history is the simulation of history, and it may involve impersonation. For example, the Julian of Gore Vidal, whatever be the quality of the scholarship.

A further criterion is the purpose of the writing, or the motive behind it—and the author's own professions come into the count. Reference can no longer be delayed to Robert Graves. That is, to his King Jesus, which sold more than a hundred thousand copies. His recent biographer came out with a firm statement, namely 'the fact that Graves believed what he was writing to be the historical truth'.⁴ That disclosure is quite alarming for estimate of the biographer no less than the author.

⁴ M. Seymour-Smith, Robert Graves (1982), 393. Credulity is contagious.