If you want a golden rule that will fit everybody, this is it: Have nothing in your houses that you do not know to be useful, or believe to be beautiful.
William Morris (1880) "The Beauty of Life," a lecture before the Birmingham Society of Arts and School of Design (19 February 1880), later published in Hopes and Fears for Art: Five Lectures Delivered in Birmingham, London, and Nottingham, 1878 - 1881 (1882).