Tertullian, Against Marcion 1.18
Let him have proceeded, come now, already into knowledge when he willed, when he could, when the fated hour arrived. For perhaps the anabibazon was blocking him, or some malefic stars, or Saturn square, or Mars trine. For Marcionites are also very much astrologers, not blushing at this either—to live even from the Creator’s very stars. Here must be treated the quality of revelation—whether he was worthily revealed, so that it may stand whether truly, and so he may be believed to be whom it has stood worthily revealed. For things worthy of God will prove God.
We define God first to be known by nature, then recognized by doctrine—by nature from works, by doctrine from preachings. But for whom there is no nature, natural instruments do not avail. Therefore he ought at least to have worked revelation of himself by preachings—especially to be revealed against him who by works of both creation and preaching, so many and so great, had scarcely yet filled the human with faith. How then was he known? If by human conjecture, I deny that God can otherwise be known than through himself—not only challenging to the Creator’s form but also to the condition both of divine greatness and of human mediocrity, lest the human seem able to be greater than God, who by his own powers somehow dragged him into the public of recognition, not willing of his own accord to be known—when human mediocrity more easily knows how to fashion gods for itself according to the experiments of the whole age than to pursue the true, whom they already understand by nature.
Otherwise, if a human will invent a god as Romulus invented Consus and Tatius Cloacina and Hostilius Pavor and Metellus Alburnus and someone before this time Antinous, this will be allowed to others; we know Marcion a shipmaster, not a king nor an emperor.
Latin
Processerit, age, iam in notitiam quando uoluit, quando potuit, quando hora fatalis aduenit. fortasse enim anabibazon ei obstabat aut aliquae maleficae aut Saturnus quadratus aut Mars trigonus. nam et mathematici plurimum Marcionitae, nec hoc erubescentes, de ipsis etiam stellis uiuere creatoris. tractandum est hic de reuelationis qualitate, an digne reuelatus sit, ut constet, an uere, et ita credatur esse quem digne constiterit reuelatum. digna enim deo probabunt deum. nos definimus deum primo natura cognoscendum, dehinc doctrina recognoscendum, natura ex operibus, doctrina ex praedicationibus. sed cui nulla natura est naturalia instrumenta non suppetunt. ergo uel praedicationibus reuelationem sui debuerat operari, maxime aduersus eum reuelandus, qui et conditionis et praedicationis operibus tot ac tantis uix tamen hominem fide impleuerat. quomodo itaque cognitus est? si per humanam coniecturam, nego deum alias cognosci posse quam per semetipsum, nec tantum ad formam prouocans creatoris uerum et ad condicionem tam diuinae magnitudinis quam humanae mediocritatis, ne maior deo homo uideri possit, qui eum non ultro uolentem cognosci suis uiribus quodammodo in publicum agnitionis extraxerit, cum humana mediocritas facilius deos fingere sibi norit secundum totius aeui experimenta quam uerum sectari, quem natura iam intellegunt. alioquin, si sic homo d.-\'um commentabitur, quomodo Romulus Consum et Tatius Cloacinam et Hostilius Pauorem et Metellus Alburnum et quidam ante hoc tempus Antinoum, hoc aliis licebit; nos Marciouem nauclerum nouimus, non regem nec imperatorem.