During Lent, the Tract replaces the Alleluia sung in most other seasons, as if reflecting the start of the season of fasting in a kind of musical fast.
Each Lenten Tract offers us a point of recollection in the liturgy, a meditative pause to prepare to hear the day's Gospel.

The Sunday which heads the Lenten season takes its theme from the paradigm of all Christian fasting: Jesus' forty days in the desert.
There, the Devil tempted Jesus to show off his divinity by casting himself down from the parapet of the temple, deceitfully quoting Psalm 90: "He hath given his angels charge over thee, and in their hands shall they bear thee up, lest perhaps thou dash thy foot against a stone."

This verse carries such a powerful association with the temptation that all the Propers of the Mass for this Sunday are based on the Psalm that contains it.
The Tract for the day takes this emphasis one step further, by quoting almost every one of Psalm 90's verses.
Rarely are Mass Propers so unified.

This Tract is set as direct psalmody. That is, the successive verses of the psalm are sung one after the other, without a refrain. The choir divides, singing the verses antiphonally.

While a Tract normally comprises three to five verses of a psalm, the Tract for this day has thirteen, a length matched on only two other days of the year: Palm Sunday and Good Friday.
On those days, the Passions are sung, so the Tracts serve then as a preparation for the extended Gospels that follow.
On the First Sunday in Lent, however, the long Tract serves as an intense introduction not just to the Gospel of the day, but to the entire Lenten season, propelling us toward God our Refuge, our Protector, and our triumphant Savior.