Marcion's Gospel not being any longer extant, it is important to establish clearly the nature of our knowledge regarding it, and the exact value of the data from which various attempts have been made to reconstruct the text. It is manifest that the evidential force of any deductions from a reconstructed text is almost wholly {88} dependent on the accuracy and sufficiency of the materials from which that text is derived. The principal sources of our information regarding Marcion's Gospel are the works of his most bitter denouncers Tertullian and Epiphanius, who, however, it must be borne in mind, wrote long after his time,--the work of Tertullian against Marcion having been composed about A.D. 208,(1) and that of Epiphanius a century later. We may likewise merely mention here the "_Dialogus de recta in deum fide_," commonly attributed to Origen, although it cannot have been composed earlier than the middle of the fourth century.(3) The first three sections are directed against the Marcionites, but only deal with a late form of their doctrines.(3) As Volkmar admits that the author clearly had only a general acquaintance with the "Antitheses," and principal proof passages of the Marcionites, but, although he certainly possessed the Epistles, had not the Gospel of Marcion itself,(4) we need not now more particularly consider it. We are, therefore, dependent upon the "dogmatic and partly blind and unjust adversaries"(5) of Marcion for our only knowledge of the text they stigmatize; and when the character of polemical discussion in the early centuries of our era is considered, it is certain that great caution must be exercised, and not too much weight attached to the statements of opponents who regarded a heretic with abhorrence, and attacked him with an acrimony which carried them far beyond the limits of fairness and truth. Their religious controversy bristles with {89} misstatements, and is turbid with pious abuse. Tertullian was a master of this style, and the vehement vituperation with which he opens(1) and often interlards his work against "the impious and sacrilegious Marcion" offers anything but a guarantee of fair and legitimate criticism. Epiphanius was, if possible, still more passionate and exaggerated in his representations against him.(2) Undue importance must not, therefore, be attributed to their statements.(3)