conclusions reached by the specialists. If he has not personally made a special study of the subject he proposes to treat, he must obviously read it up, and the task is long. For the professional populariser there is a strong temptation to study superficially a few recent monographs, to hastily string together or combine extracts from them, and, in order to render this medley more attractive, to deck it out, as far as is possible, with "general ideas" and external graces. The temptation is all the stronger from the circumstance that most specialists take no interest in works of popularisation, that these works are, in general, lucrative, and that the public at large is not in a position to distinguish clearly between honest and sham popularisation. In short, there are some, absurd as it may seem, who do not hesitate to summarise for others what they have not taken the trouble to learn for themselves, and to teach that of which they are ignorant. Hence, in most works of historical popularisation, there inevitably appear blemishes of every kind, which the well-informed always note with pleasure, but with a pleasure in which there is some touch of bitterness, because they alone can see these faults: unacknowledged borrowings, inexact references, mutilated names and texts, second-hand quotations, worthless hypotheses, imprudent assertions, puerile generalisations, and, in the enunciation of the most false or the most debatable opinions, an air of tranquil authority.
On the other hand, men whose information is all that could be desired, whose monographs intended for specialists are full of merit, sometimes show themselves capable, when they write for the public, of grave offences against scientific method. The Germans are habitual offenders: consider Mommsen, Droysen, Curtius, and Lamprecht.