Adiaphora (things that are indifferent) according to Luther

I regard images, bells, Euchristic vestments, church ornaments,

altar lights and other such things as a matter of indifference. Anyone who wishes may omit them Images or pictures taken from the Scriptures and from good histories however, I consider very useful but indifferent and optional. I do not agree with the iconoclasts.

Source: The Annotated Luther, Volume 2: Word and Faith, edited by Kirsi I. Stjerna