The Liturgy of the Hours sanctifies time by spreading liturgical praises throughout the day.
Traditionally, there is prayer in the night (the old hour of Matins, composed of three sections called “vigils”; Vatican II reformed this into the Office of Readings, and gave the option to non-monks to pray it during the day), morning prayer (called “lauds,” or the hour of praise), prayer at the beginning of the day (the old hour of Prime, which Vatican II suppressed: it mostly ended up being tacked on to other hours), mid-morning, midday, mid-afternoon, evening prayer, and bedtime, or compline.
Fun fact: in the old Roman reckoning, time is counted from sunrise, with the length of “hours” adjusted according to the length of the day. Thus the “third hour” would be nine a.m., the sixth noon, etc. But a funny inversion happened in the history of Western languages. The main meal was often eaten after mid-afternoon prayer: the ninth hour, or nona hora. Thus the hour of the main meal came to be called “noon,” from nona, or ninth – but we slid it earlier and earlier, all the way up to midday.
Meanwhile, it was common to take a little rest after midday prayer, at the sixth hour, sexta hora. This nap came to be called siesta, from sexta. We have inverted noon and the siesta, but their names come from the liturgical hours that preceded them.
One of the great pushes of the liturgical reforms at Vatican II was to rediscover the sanctification of the hours in the Liturgy of the Hours. It is for this reason that the name was changed from “The Divine Office” to “Liturgy of the Hours”: to underline that the point of these prayers was always precisely to spread prayer throughout the day.
It was standard practice in the couple centuries before the Council to squish the hours together. Even a contemplative monastery might, for example, pray morning prayer, mid-morning, midday, and mid-afternoon first thing in the morning, then evening prayer, compline, and matins before dinner. Sometimes it was more confused than that: I have seen horaria of otherwise healthy nineteenth-century monasteries where morning prayer of the next day is prayed before dinner. This sort of misses the point.
It is especially strange when one sees that the traditional ways of distributing the Psalms (there were a few different ways) focuses on times of day. Psalms that mention morning go in the morning, etc. But over time, otherwise healthy religious orders lost track of this liturgical sanctification of the day.
Along with calling for the restoration of the hours to their proper places, Vatican II also called for a broader distribution of the Psalms. Traditionally, monks have prayed all 150 Psalms (plus Old Testament and Gospel canticles) every week, some Psalms every day. This is the heart of traditional monastic spirituality. But it takes a lot of time to pray it well.
One might be working along alright – and then one finds five Psalms at dinner (unless one also has to catch up on the three from mid-afternoon), another three at bedtime, and then nine in the middle of the night. Five Psalms for morning prayer might work alright – but it was immediately followed by three more for prima hora, or Prime. And then three more in the mid-morning. It’s hard to keep up with this.
Vatican II’s solution was to spread the Psalter out over multiple weeks – the Council just said “multiple,” the final decision was four. The reason for this was not to water down the Liturgy of the Hours, but to beef it up. Even contemplatives were having a hard time praying the Divine Office seriously. By diminishing the amount of material that had to be covered, the Council Fathers hoped to make it easier to pray the hours at their proper time of day, and to pray them well, really entering into the Psalms instead of just saying them quickly. They hoped to reestablish a true Liturgy of the Hours spirituality.
One way we can embrace this mentality is by cultivating the often forgotten “little hours”: mid-morning, midday, and mid-afternoon. The true spirit of the liturgy does not require us to say as many Psalms as the monks did. But if we broke three times, or even once or twice, in the course of our day to pray even one Psalm, or one part of a Psalm, or just a Hail Mary and an Our Father, we too could help to immerse all of time in prayer.