Hemp, Cannabis sativa, is one of the world's oldest sources of food and medicine, with a history that dates back ten thousand years. It relieves glaucoma, epilepsy, migraines, insomnia, asthma, the nausea associated with AIDS and chemotherapy, and a host of other conditions. It was once a staple in every American medicine cabinet, but because hemp is the plant from which marijuana is derived, it has been unavailable to consumers until recently. Now...