The moon landing 30 years ago was one of those ''happenings,'' an event that makes you remember what you were doing at the time. I certainly do. From childhood I've followed the race to the moon with fascination.

Like millions around the world, I avidly followed the four-day flight of Apollo 11, leading up to July 20, 1969, when Neil Armstrong became the first earthling to place a footprint on another world.I was 17 at the time, newly graduated from high school from a small town in the Yukon territory of Canada, spending the summer as a construction laborer to earn money for college.

On the weekend of the moon landing, I was camping with friends. I went for a post-midnight walk along the shore and stopped to watch the moon as it broke through a gap in the clouds.

The news had come a few hours earlier about Armstrong's ''giant leap.'' Standing there on the beach, I thought of Armstrong and Buzz Aldrin camped, as it were, a quarter of a million miles away on the Sea of Tranquility.

I tried to imagine what it must be like to see Earth floating like some bright Christmas ornament against the black backdrop of the cosmos. Beyond those fleeting seconds of empathy, however, no epiphany came my way.

Chalk it up to adolescent self-absorption (or maybe the absorption of beer). Yet as I walked back to the distant campfire, I looked down the beach to see the lapping water erasing the line of my footprints, extinguishing the evidence of my passage.

I looked up at the moon again and shivered, as though touched by a cold hand. Philosophy teaches that what something once meant is not necessarily what it comes to mean. Remembering that long-ago evening, I think that dictum applies to the moon landing. Back in 1969, at the height of the Cold War, the success of the Apollo 11 mission was seen as a triumph of American technological prowess, a show of the superiority of Western democracy through technology.

But three years later, the Apollo program came to an end with Apollo 17, the sixth and final lunar landing. After Apollo 11, it was widely assumed that America would soon build a permanent space station. Then would come a moon colony and, by the end of the century, humankind would be on its way to Mars.

These things didn't happen.

Sure, we continue to dabble at the edge of the cosmic ocean. There's the shuttle program, the Hubble space telescope and the Pathfinder mission that put a little robotic rover on Mars.

But with all due apologies to the shuttle astronauts, these are essentially machine events, high-tech happenings that appeal to the specialists, not the kind of feats that make a society dream of far shores and endless horizons.

Why did we not go on? How was the momentum of Apollo 11 lost? Several reasons quickly come to mind: NASA budget cuts, the short-sightedness of politicians, a public grown jaded. ''Been there, done that. What's next?'' But I think there's another, deeper reason. Somehow, in the wake of the moon landings, humankind lost its collective courage.

The French philosopher Blaise Pascal, writing in the 17th century, when the scientific revolution was just beginning, reacted to the revelation that the universe was much bigger than the cozy cosmos envisioned by medieval metaphysics.

Pascal wrote, ''When I consider . . . the little space which I fill, and even can see, engulfed in the infinite immensity of space of which I am ignorant, and which knows me not, I am frightened . . . .'' Did something similar happened to humankind following the moon landings? Perhaps at some deep level of our collective psyche, we scared ourselves with the audacity of what we had done.

It was as though by landing on the moon, we had come to the shore of a vast ocean, stood for a few moments on the water's edge. Then, in the face of that infinite immensity, we retreated to the safety of our little campfires.

Have we retreated too far? Maybe, as Andrew Chaikin, the author of ''A Man on the Moon,'' writes, the Apollo moon landings were a historical fluke, a 21st century event dropped into the 1960s by the exigencies of the superpower rivalry between the Soviet Union and the United States.

The late Stu Roosa, who orbited the moon on Apollo 14, once expressed disbelief at the ending of the Apollo program. ''It's like we started building this beautiful thing and then we quit.'' Exactly.

The question we face on this anniversary is whether, as a civilization, we will settle for a few aging footprints as the only evidence of our confrontation with the cosmos.