Anniversaries are, strictly speaking, not necessary, but neither is art, friendship or many other of the most important things in life. We observe them by taking time out of the present to remember the past. It is a way of “marking time,” of measuring ourselves against the great and the bad who have foregone us.

Right now, the Library of Congress is exhibiting drafts of Lincoln’s Emancipation Proclamation in his own hand, in honor of its 150th anniversary. I recommend viewing these profound two pages of Lincoln’s cursive, which show us both the boldness and the vulnerability of the greatest of our leaders.

It is hard to believe how long ago it was: not very long at all. A century and a half is, from the perspective of history, or even a lifetime, not much. It is two lifetimes, back to back. In the course of human history, it is a dream of a shadow; from the perspective of universal history, it is nothing at all.

And yet, on Martin Luther King Day, of all days, the United States inaugurated our first black president for the second time.

Martin Luther King’s rise to power and influence occurred just over a century after the Emancipation, one long lifetime’s distance. Even in that time, as difficult and full of hatred and scorn as it was, remarkable, astounding progress was made, not just among Dubois’s “Talented Ten,” but among the entire black community, and, indeed, the nation as a whole. Fighting in World Wars had made men more tolerant of those from different religions and backgrounds; desegregation of the armed forces made them see through the foolishness of racial prejudice.