The main melody is from an old song. The canticle refers to the counterpoint added to harmonize the main melody.
In Medieval times, the herbs mentioned in the song represented virtues that were important to the lyrics. Parsley was comfort, sage was strength, rosemary was love, and thyme was courage.
The things the singer asks for in Scarborough Fair are all impossible. A shirt with no seams. An acre of land between the sea and the seastrand (beach). To harvest grain with a leather blade (leather isn't very sharp), and bundle the stalks with heather (a fragile twig-like flower; doesn't make for very good rope or string).
