The goodness of monkeys (Nietzsche once observed) makes it unlikely we can possibly be descended from them; but then Nietzsche knew little of monkeys, and my own view is that they are no better than we are.

And when I meet a slug, as I do with tremendous frequency since my garden resembles a slug preserve, I have a little trouble thinking of him as a cousin. But the point is, it is impossible for people today to regard the animal and vegetable kingdoms as separated from us by those gulfs that we used to think lay between us. The view now is that we're all in this together.

We are not like dogs or monkeys, but we are not so estranged from them as we once were. Brother slug is the greeting we are coming to.

The Smithsonian Institution, which must not be supposed to have the same regard I do for dogs, say, is one of the great forces all the same in the development of this century's consciousness that life is a web rather than a series of ascending pinnacles. And the National Museum of Natural History, which today observes its 75th anniversary, has seen 125 million visitors through its doors. The bulk of them, no doubt, have been young boys on fire to see the mummy display, and that wonderful man who turned to soap because of chemicals in the ground water after he was buried, but at least they had to pass the great stuffed elephant or the dinosaur skeletons or the fabulous coral reef on the way. The coral reef, by the way, cannot be seen until early May, since construction work on a great display of Maine marine life obscures it.

And culturally speaking it is a loftier excursion to see the real man turned to soap than to waste time on public television (an important institution for its programs on nature) during its money-raising and narcissistic mode as at present.

Natural History, in honor of its birthday, will be closed from 3 p.m. onward today, so don't go then. The staff is going to observe (and the public, too, if it wishes) the unveiling at 3:30 this afternoon of two natural objects at the Mall entrance, outdoors. One is an eight-ton hunk of banded iron ore from Michigan and the other is some petrified logs from Holbrook, Ariz., brought here on a flatbed truck. The mayor, city council and other notables of the region will be present. The ore and petrified wood will be permanent displays, and a better choice than stone lions or Greek gods (for which their pedestals were originally designed, but which have remained bare for all these years).

Then the museum staff will repair indoors for cake, a huge one in the shape of the museum building, and champagne. Just for the learned laborers of the museum -- you and I are not expected, though it would be agreeable to learn whether the cake will be set atop the big coffin box that holds the giant squid that is pickled. Some say the fumes would render the cake inedible; others say nonsense.

In some ways, you may think, it would have been comfortable to live in those centuries in which we were lords of creation. Now we have this uneasy suspicion that the snail darter is as important in the great scheme of things as we.

And it certainly would be nicer if we could maintain the views of childhood, that Mother Nature orders all things admirably. There are still people who think nature is just wonderful, the way the species depend on each other, but the only people who think so are also members of the Flat Earth Society or the ones who hope still to go to the moon to prove it's Brie.

The marvelous "Nature" series on television shows us how hard the little lions have to run to chew up a gazelle, and how bugs lay eggs in other bugs to hatch out and devour the host. It is haphazard and messy, and from a humanitarian point of view the best you can say of Nature's Magnificent Plan is that some things have died off and others haven't, not that it proves anything of consequence.

It is not Darwin's fault that people got the idea that whatever survives is superior to what has not survived. Dinosaurs died not because they were dumb but because they did not reproduce faster than they perished. For all anybody knows and for all that Mother Nature cares, the greatest human mind of all time may have belonged to a Flemish peasant who died of a rock falling on him in 1360. It is interesting to notice what survives, but survival hardly suggests superiority to me. Cockroaches are of course ancient and seem to be adaptable and likely to survive forever, unless of course they die out, but they are not necessarily superior to tigers, who are now disappearing.

The great thing about nature is that we are in it and it is in us, so time spent observing the natural world has at least the merit of time spent on a real and relevant subject, as distinct from such fantasies as money. Nobody can deny that the study of nature has transformed the human world more than any other factor, a study that evenhandedly dispenses central heating and atomic bombs, and offers equally the sparkling dog and the fatal virus.

At first I thought it odd for a museum to celebrate its jubilee by closing its doors at 3 p.m., but the more I think of it the better I like the idea. We do well to pause, contemplating nature, and meditate a little instead of endlessly counting things.

The biologist Jean Rostand observed that living on intimate terms with nature, one inadvertently becomes different from other people. Her silent language penetrates, saturates, persuades one gently of the insufficiency of all human speech.

Or perhaps of the futility of it.