Maybe there’s a European understanding of “interstice” with which I’m unfamiliar. Pretty sure the CDWDS means “solstice.” But that may be a troublesome term. An interstice is an in-between period, as used here, and suggestive of all of winter. But I wouldn’t see winter as merely a bridge between harvest and planting, between Fall and Spring. In human culture and our practical experience, winter is full of its own qualities.
100. Advent is celebrated during the Winter interstice in the northern hemisphere. This indicate a change of seasons and a moment of rest in many spheres of human endeavor. Popular piety is extremely sensitive to the vital cycle of nature. While the Winter interstice is celebrated, the seed lays in the ground waiting for the light and heat of the sun, which begins its ascent with the Winter solstice, and eventually causes it to germinate.
In those areas where popular piety has given rise to the celebration of the changing season, such expressions should be conserved and used as a time to pray the Lord, to reflect on the meaning of human work, which is a collaboration with the creative work of God, a self-realisation of the person, service to the common good, and an actualization of the plan of redemption(Cf. Gaudium et Spes 34, 35, 67).
Not to understate our reliance on the weather patterns in temperate zones, the world’s people are largely urban today. And where they’re not, the concerns of cities and their populations drive much ex-urban activity.
Will the old aspects of winter culture fail to touch deeply into people’s imaginations in the decades and centuries to come? What new developments will we see that take into account the year-round pace of life, and technology’s conquest of cold?
The Directory on Popular Piety and the Liturgy is online at the Vatican site.