During the Middle ages, and even in the Renaissance and until the 18th century, eyelashes were not styled. Women, in general, removed eyelashes and eyebrows in order to give more importance to the forehead, which was the most important feature in females’ faces at that time.
Women were not supposed to exhibit their hair in public, and by several ecclesiastical edicts, the Catholic Church condemned that practice as an offense to God and the church, and a sin. It obviously included eyebrows and eyelashes.
image: Petrus Christus, Portrait of a Young Woman (detail), Netherlandish, c. 1470