And here we can put these four things, as also above, namely:
Rejoicing at the words of God in the spirit,
Being sad according to the cross in the flesh,
Rejoicing at the reality of the world in the flesh,
Being sad at the cross in the conscience or spirit.
Joy inwardly over the Word.
Joy outwardly over the reality.
And
Sadness externally over the lack of the reality.
Sadness inwardly over the lack of the Word.
Therefore happy is the sadness of the faithful, which has such joy with it, and unhappy is the joy of the unbelievers, which has such sadness with it. This joy of the former is founded on the Word of the Lord, which abides forever, while the joy of the latter is founded on the flesh, which is grass because its flower has dried up and fallen (Is. 40:7). (Luther’s Works, v. 11, p.521)

This also must be noted, that as the Word of God appears to the carnal to be lacking much and in many things, so it appears to the spiritual to abound in all things like many spoils. As in the figure of the children of Israel, who seemed to be lacking everything in the wilderness, so that even the manna was sickening to them, complaining that they were in a desert of barrenness, so it is necessary for the hearers of the Word of God to be led into the wilderness where there is nothing that the flesh demands. But when the flesh has been crucified and all that is of the flesh has been removed, only the spirit should be fed and led into the land of promise, that is, the spiritual man.

Therefore the carnal man necessarily murmurs here, because he finds nothing that pleases him. Thus the more carnal and worldly a man is, the more he has to bring up against the Word of God. And what wonder? Since it is altogether foolishness to him, he knows nothing useful in it. Therefore great is the praise of the church, which has the Spirit so abundantly that it esteems only the words of God, to rejoice in them above all spoils. Rejoicing in those things which to others seem to be sad things and nothings without a doubt puts a great void between the latter and the former. (Luther’s Works, v. 11, p.520-521)

This one argument, I say, would be abundantly enough, even if it were the only one, to demonstrate this. If there is neither wisdom nor knowledge nor reason in death, whither we are hastening (Eccl. 9:10), then the world is that way by which we hasten to such great wretchedness. And so, the faster it hastens, the more it shares in its own end (like every motion). This is surely what Hezekiah says (Is. 38:18): “Neither shall death praise Thee, nor shall they who go down into the pit look for Thy truth.” If they who go down do not look for it, how much more is this true of those who are already in the pit and have gone down! For those who are going down are the ones in the world of whom he said that they are hastening to death.

Therefore, O thick darkness of Egypt, which ignores such great benefits of the Word of God! But, O blessed light of the church, which still sees, so that it also rejoices at these: In the midst of persecuting and threatening princes she still has more joy within than grief without; the words of God do more to strengthen the spirit than the scourges of men to weaken the flesh. The latter is afflicted with the pains of tormentors, the former is consoled by the strength of words. Wonderful exchange, that words prevail over things, things that are contrary and exceedingly strong! As Isaiah promises (Is. 50:4): “The Lord has given me a learned tongue, that I should know how to uphold by the Word him who is weary.” “By the Word,” he says, namely, by the naked Word without the reality set forth, but not without the reality to be set forth. (Luther’s Works, v. 11, p.519-520)