"The dose makes the poison” is a maxim that has been generally accepted since the time of Swiss physician Paracelsus (1493?1541). This is especially true of medicinal plants, like those on the limited-edition miniature sheet. Certain plants contain active ingredients which can be used to cure or treat illnesses. Knowledge of some of these is ancient and still comes in useful today. If the dose isn’t right, however, these plants can actually be poisonous. The miniature sheet continues the yearly series of limited-edition stamps made using a special production technique, such as the recent «Record» (special lacquer with audio), «Goldvreneli» (gold embossing) and «Quince scent» (perfumed stamp). In 2018, the chosen technique is steel engraving. The four medicinal plants which are depicted are inspired by the book of herbs by the Italian doctor and botanist Pietro Andrea Mattioli (1501?1577). He was the first to describe plants which arrived in Central Europe in the 16th century, such as the tomato from America and the horse chestnut from the Balkans. His herbal was extremely popular and continued to be printed into the 17th century. To reflect this heritage, the motifs on the miniature sheet are designed to resemble those on old educational wall charts.