Tuesday was another one of those roller coaster days that moved between an extreme new high and a troubling low in the evolving cultural history of the nation.

President Obama’s nomination of Judge Sonia Sotomayor to become the first Hispanic justice on the U.S. Supreme Court marked yet another high-water mark in the dizzying transformation that has been unleashed on American society since Obama’s inauguration only a few short months ago.

On the down side, it was followed in only two hours by the announcement of the 6-1 decision by the California Supreme Court that Proposition 8, a state constitutional amendment referendum prohibiting gay marriage, was in fact constitutional.

The day was eerily similar to last November 4, when the epochal victory of Obama in the presidential election, and the incredible elation that issued from that among all fair-minded Americans, was sharply tempered late in the night, when the results came in from California that the prejudicial Proposition 8 had passed.

It was the poet Schiller who wrote that the most creative human emotion is what he called “melancholy.” It is derived from the sense of “not yet” that impels humans to strive for greater achievements.

It is also a good antidote to wild mood swings that attend America’s fixation on either winning or losing at nearly everything we do.

So the creative emotion works best to move the process forward, to put inflection points like those this Tuesday in context as mere moments in an unfolding of history toward the emergence of a nobler species.

If the truly inspiring nomination of Judge Sotomayor, and what it represents symbolically for the advance of human rights and equality in spite of differences, were applied to the Proposition 8 case, there would surely have been a different outcome in California. Those who are fighting for full equality for lesbians and gays can take some heart from that going forward.

The one phrase that rang out in Obama’s announcement of his nominee Tuesday morning was the U.S. Constitutional guarantee of, “Equal protection under the law.”

That foundational constitutional principle will eventually prevail and be extended to the full enfranchisement of the last class of Americans who are denied it, its lesbian and gay citizens both living and yet unborn.

It warrants continual repetition that the U.S. Supreme Court already laid the basis for the extension of full equality in its 2003 Lawrence Vs. Texas ruling.

Embedded in that ruling, which struck down all state and local laws prohibiting same-sex sexual acts in private, was the notion that laws shall not discriminate against any “class of persons.” Gays and lesbians were identified as “a class of persons.”

That ruling was exploited by the right wing to launch a furious backlash that was pivotal in the re-election of George W. Bush in 2004 and helped galvanize fundraising channels for the right through state-by-state constitutional amendment initiatives.

But the cultural tide is turning, and it’s been only six months since the November election, and three months since the Obama inauguration.

The opinion of the one dissenting justice on the California Supreme Court released Tuesday lays a solid foundation for the ongoing struggle.

Justice Carlos R. Moreno noted that “equal protection” is “by its nature, inherently countermajoritarian.” He wrote, “It cannot depend on the will of the majority for its enforcement, for it is the will of the majority against which the equal protection clause is designed to protect…Proposition 8 represents an unprecedented instance of a majority of voters altering the meaning of the equal protection clause by modifying the California Constitution to require deprivation of a fundamental right on the basis of a suspect classification. The majority’s holding is not just a defeat for same-sex couples, but for any minority group that seeks the protection of the equal protection clause.”