“…Of the flower of violet and of sugar is made sugar of violets, of the same flower and of honey of violets and of the same flower and oil is made of violets. Whichever it is desired to make, put the flower in the honey, oil or sugar, leave it there for a period of time and press it thereafter, and it will be as we have said… pound the flower of violet and put it together with oil in a glass vessel, under the sun in summer time for fifteen days, and it will be an excellent oil which will give relief from every hot bad complex of the body (especially headache). This oil has four virtues, to make smooth what is rough, to cool what is hot, to soften what is hard and to ease the stoppage and bind that affect the intestines.”

Tadhg Ó Cuinn, Irish Materia Medica, 1452