3. After a general preliminary idea of the history has been obtained from these sources, in order to prevent being confused with details; it is necessary to resort next to the original sources of information, without careful study of which the history must lack a real basis. In reference to the early unbelievers, the direct materials are lost; but the contemporary replies to these writings remain. In the case of later unbelievers, both the works and the answers to them exist. It will be presumed that in so large a subject the writer cannot have read all the sceptical works which have been written, and are here named. With the exception however of Averroes and of the Paduan school,(27) in which cases he has chiefly adopted second-hand information, and merely himself consulted a few passages of the original writers, he has in all other instances read the chief works of the sceptical writers, sufficiently at least to make himself acquainted with their doubts, and in many cases has even made an analysis of their works. The reader will perceive by the foot-notes the instances in which this applies. It may be due to some of the historians who have made a special study of particular periods from original sources, to state, that so far as his limited experience extends he can bear witness to their exactness. Leehler’s work on English deism, for example,(28) is a singular example of truthful narrative; and Leland’s,(29) though controversial, is worthy of nearly the same praise. 4. There remains a fourth source of materials in the separate monographs on particular men, opinions, or schools of thought. We shall enumerate these according to the order of the lectures; dwelling briefly on the majority of them, as being described elsewhere; and describing at greater length those only which relate to the history of the theological movements in Germany described in Lectures VI. and VII.; inasmuch as references are there frequently made to these works without a specific description of their respective characters. In relation to the early struggle of Paganism against Christianity,(30) the work of Lardner, _Collection of Ancient Jewish and Heathen Testimonies to the Truth of the Christian Religion_ (1764-7) (Works, vols. vii.-ix.), is well known for carefulness of treatment and the value of its references. Portions also of the works of J. A. Fabricius, especially his _Bibliotheca Græca_ and _Lux Evangelii_ (1732) are useful in reference to the lost works, and for bibliographical knowledge: also a monograph by Kortholt, _Paganus Obtrectator_ (1703), on the objections made by Christians in the early ages, gathered from the Apologies.