Melanchthon: church doctrine is taken from God's revealed sayings, not from demonstrations
And Melanchthon speaks wisely in the preface to the Loci Communes. The doctrine of the church, he says, is not taken from demonstrations, but from sayings that God handed down to the human race by sure and illustrious testimonies — sayings through which, in his immense goodness, he disclosed himself and his will.
Just as philosophy seeks what is certain, separates it from what is uncertain, and names as causes of certainty universal experience, principles, and demonstrations, so in the church's teaching the cause of certainty is the revelation of God, and what must be weighed is which sentences God has handed down.
As any sound mind finds this sentence certain — "Twice four are eight" — because it is natural knowledge, like the knowledge of principles, so let the articles of faith, the divine threats and promises, stand for us certain and unmoved. So let the penitent be certain that sins are remitted, that for the Son of God's sake he is heard, and that he is made an heir of eternal life.
But the causes of certainty differ. The mind sees the sentence about numbers by its own judgment. The articles of faith are certain because of revelation, confirmed by God's sure and illustrious testimonies — the raising of the dead and many other miracles. Yet because these are matters set outside the judgment of the human mind, the assent is weaker: it arises because the mind is moved by those testimonies and miracles and is helped by the Holy Spirit to assent.
Latin
Et sapienter Philippus Melanchthon praefat. L. C. Doctrina, inquit, Ecclesiae non ex demonstrationibus sumitur, sed ex dictis, quae Deus certis & illustribus testimoniis tradidit generi humano, per quae immensa bonitate se & suam voluntatem patefecit. Ac, ut in philosophia quaeruntur certa, & discernuntur ab incertis, & causae certitudinis sunt experientia universalis, principia & demonstrationes: ita in doctrina ecclesiae, certitudinis causa est revelatio DEI, & considerandum est, quae sententiae a Deo traditae sunt. Ut certa est cuilibet sano haec sententia, Bis quatuor sunt octo, est enim naturalis notitia, ut principiorum: ita sint certi nobis & immoti articuli fidei, comminationes & promissiones divinae; ita certum sit, agenti poenitentiam remitti peccata, propter Filium Dei exaudiri se, & fieri haeredem vitae aeternae. Sed causae certitudinis diversae sunt. Sententiam de numeris mens suo judicio videt. At articuli fidei certi sunt propter revelationem, quae certis & illustribus testimoniis Dei confirmata est, ut resuscitatione mortuorum, & multis aliis miraculis. Sed quia sunt res extra judicium humanae mentis positae, languidior est assensio, quae fit, quia mens movetur illis testimoniis & miraculis, & juvatur a Spiritu sancto ad assentiendum.