While Martin Luther (1483-1546) was a professor at Wittenberg, he devised a seal which was meant to be expressive of his theology. In a letter to a friend Luther explained the symbolism of his seal.
A black cross rests on a red heart “to put me in mind that faith in Christ crucified saves us.” The heart rests on the centre of a white rose “to show that faith causes joy, consolation and peace. The rose is white, not red, because white is the ideal colour of all angels and blessed spirits.”
The rose is fixed in a dark blue sky “to denote that such joy of faith in the spirit is but an earnest and beginning of heavenly joy to come, as anticipated and held by hope, though not yet revealed.”
The sky is surrounded by a golden ring “to signify that such bliss in heaven is endless, and more precious than all joys and treasures… Christ, our dear Lord, He will give grace unto eternal life.”