People say the effect is only on the mind. It is no such thing. The effect is on the body, too. Little as we know about the way in which we are affected by form, by color, and light, we do know this, that they have an actual physical effect. Variety of form and brilliancy of color in the objects presented to patients, are actual means of recovery.

Notes on Nursing: What it Is, and what it is Not (ed. 1860)