Friday's Supreme Court decision will go down in history as the day the Court affirmed a constitutional right to same-sex marriage.

But the two most important sentences in the opinion were a reminder that this decision was really about much more than that. The opinion does not merely address the needs of one particular interest group. Rather, it is remedying a far bigger wrong: the unconstitutional exclusion of some Americans from one of the most important institutions in American life.

Loving did not ask about a "right to interracial marriage"; Turner did not ask about a "right of inmates to marry"; and Zablocki did not ask about a "right of fathers with unpaid child support duties to marry." Rather, each case inquired about the right to marry in its comprehensive sense, asking if there was a sufficient justification for excluding the relevant class from the right.

It would be easy to skim over those lines: A string of case law references and "excluding the relevant class" do not draw the eye. But the fundamental point being made here could not be more important. Marriage — not same-sex marriage, or interracial marriage, or marriage behind bars, or marriage under the pall of unpaid child support obligations, but marriage itself — is one of the most important institutions of American life. And so any law that excludes an entire class of people from that institution is fundamentally incompatible with the freedoms guaranteed by the US Constitution. That is what today's opinion is about, and that is why it matters to everyone in this country, not just the same-sex couples who have finally had their constitutional rights recognized.

Today's analysis echoes and cites a different legal opinion, which still contains the best description I have ever read of the importance of marriage — so much so that I included it in my own marriage ceremony in 2009.

In Goodridge vs. Department of Public Health, the Massachusetts Supreme Court held that its state constitution guaranteed same-sex couples the right to marry. Writing for the majority, Chief Justice Margaret Marshall explained the vital importance of marriage to American life:

Civil marriage is at once a deeply personal commitment to another human being and a highly public celebration of the ideals of mutuality, companionship, intimacy, fidelity, and family. It is an association that promotes a way of life, not causes; a harmony in living, not political faiths; a bilateral loyalty, not commercial or social projects. Because it fulfills yearnings for security, safe haven, and connection that express our common humanity, civil marriage is an esteemed institution, and the decision whether and whom to marry is among life’s momentous acts of self-definition.

Today, the Supreme Court affirmed that all Americans, regardless of whom they love, should have the right to that momentous act of self-definition, and the same opportunity to fulfill their own yearnings for security, safe haven, and connection that express their common humanity.

The final paragraph of today's opinion is a moving description of the value of that right:

No union is more profound than marriage, for it embodies the highest ideals of love, fidelity, devotion, sacrifice, and family. In forming a marital union, two people become something greater than once they were. As some of the petitioners in these cases demonstrate, marriage embodies a love that may endure even past death. It would misunderstand these men and women to say they disrespect the idea of marriage. Their plea is that they do respect it, respect it so deeply that they seek to find its fulfillment for themselves. Their hope is not to be condemned to live in loneliness, excluded from one of civilization’s oldest institutions. They ask for equal dignity in the eyes of the law. The Constitution grants them that right.

It has been far too long in coming, but today is a wonderful day.