"By the venerable tradition of the universal Church, lauds as morning prayer and vespers as evening prayer are the two hinges on which the daily office turns; hence they are to be considered as the chief hours and celebrated as such."(General Instruction on the Liturgy of the Hours,#37.)
That's the reason that versions of the Liturgy of the Hours focus on Morning and Evening Prayer. If someone wants to pray the liturgical hours, these are the ones to start with. And for many laymen, these are the only ones that are ever used. (Although to take one more step and add Compline before bedtime would not be a bad idea. But I digress.)
Let's explore this idea of “hinges”. The Latin for “hinge” is cardo. The Church's government “hinges” upon the college of Cardinals, those bishops of elevated rank who advise the Pope and elect new popes from their ranks. Then there's the four cardinal virtues: prudence, justice, temperance, and fortitude. These four are the virtues of natural morality. They are the natural “hinges” upon which hang the higher, theological virtues.
But hinges just aren't for hanging things. Hinges hold a door to a building, enabling it to open and shut.
I think that's how we can appreciate morning and evening prayer—lauds and vespers—in our lives. The psalms of morning prayer open the door on our day, welcoming the rising sun as God's daily gift, recalling the opening tomb of Easter morning, and opening our hearts to a daily new beginning.
Vespers, or evening prayer, gently shuts the door as the working day draws to an end. We shut the door on the day's busy-ness, and enclose ourselves in our home, the domestic church, where we offer an “evening oblation” of the day's accomplishments. With evening prayer we also close the door on the day's troubles, on our failures, and rest in the peace that only Christ can give.
Whether or not you pray the liturgy of the hours, regular morning and evening prayer of some kind can, and should form the “hinges” of your day. Praising God each morning as the day begins, and begging his help for all the adventures that day will bring. Ending each day by placing it into his hands,and resting for a moment in his all-knowing, almighty, all-loving heart. He stands at the door and ever knocks. Those good, sturdy hinges of daily prayer will keep the door in working order.