Herbals are books describing plants and their uses - whether for medicine of cookery. Elizabeth (Blachrie) Blackwell's herbal was issued between 1737 and 1739 and contains many of her own beautiful drawings of plants.
Elizabeth was born in Aberdeen, Scotland in 1700 and married Alexander Blackwell, a printer. It was in order to get money to have him released from debtors prison that she published her work. He was released and promptly left for Sweden without his wife. He was hanged there for treason in 1748.
Elizabeth died in 1758. You can read more about Elizabeth Blackwell at the British Library site.
Throughout the Outlander series of books we learn of Clair's love of and fascination for medicinal plants and natural remedies. In Dragonfly in Amber Clair studies a herbal she was given as a gift by Brother Ambrose when she and Jamie left the Abbey. That got me curious to find out what they were. This one is just beautiful.
So Mullein is good for toothache - must have been useful in the days before modern dentistry!