Why is green used during Ordinary Time in many Western churches?

In many Western churches, the use of green during Ordinary Time serves as a liturgical color with two primary historical and symbolic interpretations:

• Compromise and Distinction: Historically, the modern color sequence for the Roman Catholic Church was outlined by Pope Innocent III. In his treatise De sacro altaris mysterio, he designated green as a "compromise color" to be used on days not requiring the specific symbolic colors of white (purity), red (passion/martyrdom), or black (mourning).1
• Symbol of Hope: In contemporary liturgical practice, green is frequently interpreted as a symbol of hope. This association reflects the growth and vitality of the church during the periods of the liturgical year that fall outside the major seasons of celebration or penitence.2

While Innocent III’s original symbolism was rooted in allegorical interpretations of Scripture, such as the Song of Solomon, the use of green has evolved into a standard tradition for marking the weeks of Ordinary Time that occur between the Christmas and Lent seasons, as well as the period following Pentecost.21