Here we find an in-depth discussion of aromatherapy. Included are the effects of hydrosols, made from various plant materials, on human health. Apparently (I know little about aromatherapy), hydrosols represent a different approach to the better-known one of using essential oils and absolutes. Hydrosols contain only the active component and water. Rose water is one example. Hydrolats, at least implied by the cover, are hydrosols specifically designated for aromatherapy.