Tertullian, Against Marcion 18
Let him proceed, then, into recognition — when he wished, when he could, when the fatal hour arrived. Perhaps the ascending node blocked him, or some baleful influence, or Saturn in square, or Mars in trine. After all, the mathematicians are mostly Marcionites, and they don't blush to admit it; they live by the very stars of the Creator.
Here we must test the quality of the revelation: whether he was revealed worthily, so that it holds together; whether truly, so that he may be believed to be what he was worthily revealed to be. Things worthy of God will prove God.
We define God as first to be known by nature, then recognized by doctrine — nature from his works, doctrine from his preachings. But where there is no nature, natural instruments fail. So he ought to have effected his own revelation through preachings, especially against the one who needed revealing — the one who, despite works of creation and preaching so many and so great, had barely managed to fill man with faith.
How, then, was he known? If by human conjecture, I deny that God can be known except by himself — and not merely to the form of the Creator, but to the condition of such divine greatness and human mediocrity, lest man appear greater than God. God did not will to be known; he was dragged into public recognition by his own powers. Human mediocrity finds it easier to fabricate gods for itself, based on the experiments of all time, than to follow the truth that nature already grasps.
Otherwise, if man presumes to comment on God this way, then let others do as Romulus did with Consus, Tatius with Cloacina, Hostilius with Pavor, Metellus with Alburnus, and some before this time with Antinous. We know Marcion as a shipowner, not a king or 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.