Advent as sacrament

I have been interested in the idea that maybe things in addition to The (dominical) Sacraments (of the gospel) might be thought of as sacramental so I thought I might jot down this quote from J Neil Alexander:

Is Advent a preparatory fast in preparation for the liturgical commemoration of the historical birth of Jesus in Bethlehem, or is Advent a season unto itself, a sacrament of the end of time begun in the incarnation and still waiting on its final consummation at the close of the present age?

"A Sacred Time in Tension" in Liturgy vol. 13, no. 3, quoted in Fleming Rutledge, Advent: The Once & Future Coming of Jesus Christ (Eerdmans, Grand Rapids, 2018) p. xi