Verily the most necessary thing is contentment under all circumstances; by this one is preserved from morbid conditions and from lassitude. Yield not to grief and sorrow: they cause the greatest misery. Jealousy consumeth the body and anger doth burn the liver: avoid these two as you would a lion. (Bahá’u’lláh, cited in ‘Bahá'u'lláh and the New Era’, p. 108; The Compilation of Compilations, vol. I, Some Aspects of Health, Healing, Nutrition and Related Matters)