Earthly trouble did but turn the painter's gaze heavenwards, and his art, which in time of trial came as consolation, grew all the more spiritual as it passed through waters of affliction. Few painters, even in the good old days, obtained so sympathetic a public. Belief in a mission begat like faith in others, and so solicitations came for drawings and pictures far in excess of available time and strength. Certain commissions could not be entertained, secular subjects had been long eschewed, religion and the Church were alone accounted worthy of service. Therefore, in genial mood, was the great picture for Cologne Cathedral undertaken and carried out. The work occupied no less than nine years; the cartoon was already in course of preparation in 1846, and the picture reached completion in 1855. But, as with other engagements, the negotiations and preliminary correspondence extended over a longer period. Thus, as far back as 23rd August, 1829, Overbeck, while working on the Assisi fresco, writes from Santa Maria degli Angeli to his friend Mosler, stating that the Düsseldorf Kunst-Verein wish for some picture; but prior engagements stand in the way: he foresees that on the return to Rome he will find his studio crowded with works begun, but still unfinished, besides sketches of all sorts and sizes for pictures not even commenced. He therefore asks for delay, and ends with apologies for not writing more on the parental plea that "though it is Sunday, I have long given my promise to my boy Alfons, whose tenth birthday is to-day, that he shall have a ride on a donkey, and I am all the more obliged to keep my word because my fresco work here compels me for the moment to neglect him. We are all, thank God, very well, and enjoy a thousand blessings in this abode of Paradise." Three months later he writes under mistaken impressions as to the character of the commission; he wishes to know the architectural style of the church, and hopes it may be Gothic; he desires accurate measurements, because the picture must appear to belong to its destined place, and then ends in the following characteristic terms: "I repeat once more that the commission fills me with utmost pleasure, but to you I must confide my great anxiety, that I fear this picture is destined for a Protestant church, as I hear it is to be for some newly-built church. Should this, indeed, be the case, then pray try to give the whole thing another direction, as such a commission would not suit me at all, and to refuse it would be very disagreeable to me."