September 23

…when the constitution is in a state of equilibrium, there is no doubt that whatever is relished will be beneficial to health. Observe how an animal will graze in a field where there are a hundred thousand kinds of herbs and grasses, and how, with its sense of smell, it snuffeth up the odours of the plants, and tasteth them with its sense of taste; then it consumeth whatever herb is pleasurable to these senses, and benefiteth therefrom. Were it not for this power of selectivity, the animals would all be dead in a single day; for there are a great many poisonous plants, and animals know nothing of the pharmacopoeia. And yet, observe what a reliable set of scales they have, by means of which to differentiate the good from the injurious. Whatever constituent of their body hath decreased, they can rehabilitate by seeking out and consuming some plant that hath an abundant store of that diminished element; and thus the equilibrium of their bodily components is re-established, and they are rid of their disease. 
- ‘Abdu’l-Baha  (‘Selections from the Writings of ‘Abdu’l-Baha’)