There are many passages in which he merely claims to have been enlightened in his ruminations and labours and thus led to embrace the real, saving truth; less frequently do we hear of any actual, sudden inspiration from above. Where he does claim this most distinctly is in the matter of the discovery of his chief doctrine, viz. assurance of salvation by justifying faith, vouchsafed to him in the Tower of the Wittenberg monastery. The fact that his mode of expression varies may be explained not merely by his own involuntary wavering, but by the very difficulty of imparting his favourite doctrine to others. His frame of mind, outward circumstances and the character of his hearers or readers were the cause of his choice of words. With his friends, for instance, more particularly the younger ones, and likewise in his sermons at Wittenberg, he was fond of laying stress on what he had once said to the lawyers when they molested him with Canon Law: “They shall respect our teaching, which is the Word of God spoken by the Holy Ghost through our lips.”[292] When speaking to larger audiences, on the other hand, he does not as a rule claim more than a gradual, inner enlightenment by God, which indeed partakes of the nature of a revelation, but to which he was led by his work and study and inward experience. In the presence of the fanatics he became, after 1524, more cautious in his claims, owing to the similar ones made on their own behalf by these sectarians. Yet the idea of an assurance born of God lies at the bottom of all his statements. He worked himself into this belief until it became part of his nature.[293] He had to face many doubts and scruples, but he overcame them, and, in the latter years of his life, we hear little of any such. His struggle with these doubts, which clearly betray the faulty basis of his conviction, will be dealt with elsewhere.[294] “I am certain and am determined to feel so.” Expressions such as this are not seldom to be met with in Luther’s letters and writings.[295] An almost appalling strength of will lurks behind such assurances. Indeed, what impels him seems to savour more of self-suggestion than of inward experience. To the objections brought forward by his adversaries he frequently enough merely opposes his “certainty”; behind this he endeavours to conceal the defects of his proofs from Scripture, and his inability to reply to the reasons urged against him. His determination to find conviction constitutes one of Luther’s salient psychological characteristics; of the Titanic strength at his disposal he made proof first and foremost in his own case. * * * * * Luther also succeeded in inducing in himself a pseudo-mystic mood in which he fancied himself acting in everything conformably with a Divine mission, everywhere specially guided and protected as beseemed a messenger of God.