This is the classic seasoning used in French pates and terrines served cold. The proportions vary widely among chefs; this one is from Jane Grigson's excellent Charcuterie. Some use almost equal parts of the spices, but Larousse Gastronomique uses more than twice the amount of pepper that this recipe calls for.
Quatre-epices means four spices, but of the four traditional spices, three are always used (pepper, clove, and nutmeg) and then the fourth is either cinnamon or ginger, depending on your taste and how you're using it. I like to use cinnamon with a pork pate.