To pass gradually from a sound, prosperous, or perfect state, to one of imperfection, adversity, or dissolution; to waste away; to decline; to fail; to become weak, corrupt, or disintegrated; to rot; to perish; as, a tree decays; fortunes decay; hopes decay.
To cause to decay; to impair.
Gradual failure of health, strength, soundness, prosperity, or of any species of excellence or perfection; tendency toward dissolution or extinction; corruption; rottenness; decline; deterioration; as, the decay of the body; the decay of virtue; the decay of the Roman empire; a castle in decay.
Harmony makes small things grow, lack of it makes great things decay. Sallust
In a decaying society, art, if it is truthful, must also reflect decay. And unless it wants to break faith with its social function, art must show the world as changeable. And help to change it. Ernst Fischer