I can do no better than quote Oliver Wendell Holmes from his famous speech to the University of Virginia in 1884:
So to the indifferent inquirer who asks why Memorial Day is still kept up we may answer, it celebrates and solemnly reaffirms from year to year a national act of enthusiasm and faith. It embodies in the most impressive form our belief that to act with enthusiam and faith is the condition of acting greatly. To fight out a war, you must believe something and want something with all your might. So must you do to carry anything else to an end worth reaching. More than that, you must be willing to commit yourself to a course, perhpas a long and hard one, without being able to foresee exactly where you will come out. All that is required of you is that you should go somewhither as hard as ever you can. The rest belongs to fate. One may fall-at the beginning of the charge or at the top of the earthworks; but in no other way can he reach the rewards of victory.
When it was felt so deeply as it was on both sides that a man ought to take part in the war unless some conscientious scruple or strong practical reason made it impossible, was that feeling simply the requirement of a local majority that their neighbors should agree with them? I think not: I think the feeling was right-in the South as in the North. I think that, as life is action and passion, it is required of a man that he should share the passion and action of his time at peril of being judged not to have lived.
If this be so, the use of this day is obvious. It is true that I cannot argue a man into a desire. If he says to me, Why should I seek to know the secrets of philosophy? Why seek to decipher the hidden laws of creation that are graven upon the tablets of the rocks, or to unravel the history of civilization that is woven in the tissue of our jurisprudence, or to do any great work, either of speculation or of practical affairs? I cannot answer him; or at least my answer is as little worth making for any effect it will have upon his wishes if he asked why I should eat this, or drink that. You must begin by wanting to. But although desire cannot be imparted by argument, it can be by contagion. Feeling begets feeling, and great feeling begets great feeling. We can hardly share the emotions that make this day to us the most sacred day of the year, and embody them in ceremonial pomp, without in some degree imparting them to those who come after us. I believe from the bottom of my heart that our memorial halls and statues and tablets, the tattered flags of our regiments gathered in the Statehouses, are worth more to our young men by way of chastening and inspiration than the monuments of another hundred years of peaceful life could be.
With gratitude to those who have served and reverence who gave that "last full measure" of their devotion to our country.