His having rightly determined how Law and Gospel stood seemed to him one of his greatest achievements, in fact one of the most important of the revelations made to him from on High. “Whoever is able clearly to distinguish the Law from the Gospel,” he says, “let such a one give thanks to God and know that he is indeed a theologian.”[13] Alluding to the vital importance of Luther’s theory on the Law with its demands and the Gospel with its assurance of salvation, Friedrich Loofs, the historian of dogma, declares: Here “may be perceived the fundamental difference between the Lutheran and the Catholic conception of Christianity,”[14] though he does not fear to hint broadly at the “defects” and “limitations” of Luther’s new discovery; rather he admits quite openly, that some leading aspects of the question “never even revealed themselves clearly” to Luther, but betray a “notable” lack of discernment, and that Luther’s whole conception of the Law contained “much that called for further explanation.”[15] In order to give here a clearer picture of Luther’s doctrine on this matter than it was possible to do in the earlier passages where his view was touched upon it may be pointed out, that, when, as he so frequently does, he speaks of the Law he means not merely the Old-Testament ceremonial and judicial law, but even the moral law and commands both of the Old Covenant[16] and of the New,[17] in short everything in the nature of a precept binding on the Christian the infringement of which involves him in guilt; he means, as he himself expresses it, “everything ... that speaks to us of our sins and of God’s wrath.”[18] By the Gospel moreover he understands, not merely the promises contained in the New Testament concerning our salvation, but also those of the Old Covenant; he finds the Gospel everywhere, even previous to Christ: “There is not a book in the Bible,” he says, “which does not contain them both [the Law and the Gospel]. God has thus placed in every instance, side by side, the Law and the promises, for, by the Law, He teaches what we are to do, and, by the promises, how we are to set about it.” In his church-postils where this passage occurs Luther explains more fully what he means by the “promise,” or Gospel, as against the Law: It is the “glad tidings whereby grace and forgiveness of sins is offered. Hence works do not belong to the Gospel, for it is no law, but faith only [is required], for it is simply a promise and an offer of Divine grace. Whoever believes it receives the grace.”[19]