Gather 2 ounces of either feverfew (which I don’t use), or Yarrow, and my ancestors use the term “sustainment” which mean (at-least) 80% alcohol. Mix well and allow to sit for about 6 weeks. After the 6 weeks, strain the yarrow, and place the remaining liquid in small amber bottles for storage. They can safely store for about a year. As the recipe calls for, you will want to have a 2 to 1 ratio alcohol to herb during the brewing process.