“Our doctrine as to how we are to deal with our own uncleanness and sin is briefly this: Believe in Jesus Christ and your sins are forgiven; then avoid and withstand sin, wage a hand-to-hand fight with it, do not allow it its way, do not hate or cheat your neighbour,” etc.[111] Such admonitions strenuously to strive against sin involuntarily recall some very different assurances of his, viz. that the man who has once laid hold on righteousness by faith, at once and of his own accord does what is good: “Hence from faith there springs love and joy in God and a free and willing service of our neighbour out of simple love.” Elsewhere too he says, “Good works are performed by faith and out of our heartfelt joy that we have through Christ obtained the remission of our sins.... Interiorly everything is sweet and delicious, and hence we do and suffer all things gladly.”[112] And again, just as we eat and drink naturally, so also to do what is good comes naturally to the believer; the word is fulfilled: Only believe and you will do all things of your own accord;[113] as a good tree must bring forth good fruit and cannot do otherwise, so, where there is faith, good works there must also be.[114] He speaks of this as a “_necessitas immutabilitatis_” and as a “_necessitas gratuita_,” no less necessary than that the sun must shine. In 1536 he even declared in an instruction to Melanchthon that it was not right to say that a believer _should_ do good works, because he can’t help performing them; who thinks of ordering “the sun to shine, a good tree to bring forth good fruit, or three and seven to make ten?”[115] * * * * * Of this curious idealism, first noticed in his “Von der Freyheyt eynes Christen Menschen,” we find traces in Luther till the very end of his life.[116] In later life, however, he either altered it a little or was less prone to insist on it in and out of season. This was due to his unfortunate experiences to the contrary; as a matter of fact faith failed to produce the effects expected, and only in rare instances and at its very best was it as fruitful as Luther wished. The truth is he had overrated it, obviously misled by his enthusiasm for his alleged discovery of the power of faith for justification. He was also fond of saying—and of this assurance we find an echo in his last sermon—that a true and lively faith should govern even our feeling, and as we are so little conscious of such a feeling and impulse to what is good, it follows that we but seldom have this faith, i.e. this lively certainty of salvation.