If you're of middle age, I'll bet there are bits of history that stop you short. For me, it's images, TV footage, even text from the 1960s. I can get lost for hours.

This year marks the 50th anniversary of the start of the 1964-65 New York World's Fair, and I am thinking back to the time spent there as a kid, circling the Unisphere and standing in line for the Ford pavilion's Magic Skyway.

To help reach back, I'm going straight to the source. Not to new books like Joseph Tirella's Tomorrow-Land, with its researcher's focus on a range of external issues, but to a dust-blanketed old one that has been wedged in the back of my shelf since the summer of 1964: The Official Guide to the New York World's Fair.

The spine of this $1.25 paperback splits in two as soon as I crack it open. But I land right away on the page where Robert Moses, president of the fair, welcomes visitors while giving them a brief grilling.

"What is it you want?" he barks. "Vast forces dormant in nuggets of imprisoned sunlight? Machines that fly, think, transport, fashion and do man's work? Spices, perfumes, ivory, apes, and peacocks? . . . The products of philosophy, which is the guide of life, and knowledge, which is power? We have them all."

Vast forces. Man's work. This, I realize, was how people spoke back then. Philosophy. Life. Knowledge. Power. The 1964-65 World's Fair had them all.

Like just about anyone nowadays, I can't resist a laugh. But, by the time I get to an ad for the General Electric pavilion, I am aware that I would like at least a few of these 1960s promises back.

There is something reassuring about the tiny, well-dressed families milling on the ultrafuturistic plaza. Something marvelous in rays of nighttime lighting, in yellow splashed against aquamarine. The two-page spread looks intergalactic. It might lift off, if I did not press it down. "The General Electric Carousel of Progress," I read. "On the Avenue of Commerce, beside the Pool of Industry."

I am escaping down the outskirts of that Avenue. Slipping under the surface of the Pool. I am back there, just a boy again, believing in the biggest of promises. I admire technology, innovation. I know that, someday, I will explore the moon.

I can say the word progress here, and without irony, now that I am deep within my Official Guide. And I am not embarrassed. Oh, no. I am glad.

I may decide to hide inside a diorama. I may not come out. How could I have lost my 1960s dreams, and not replaced them? Solutions are everywhere at this fair. Nothing is unreachable.

What was the year when I gave up on rockets, inoculations, inventions - on running my palm along a brand-new car?

When did I stop expecting that something physical, not virtual, would make life better and take me where I wanted to go? "Use your head at the fair," admonishes my guidebook. "Patronize buses, rolling stock, rides, ramps, and escalators."

The world of this World's Fair, I realize, is one of adventure, of tackling problems, not of numbers. It celebrates actual things. Think nuclear fusion, think stainless steel. Not images on a screen.

At the General Motors' Futurama exhibit they seem to understand that this 1964 world is what I've been missing all this time. "Are you ready?" asks a man with a hat down at the corner of the page. I am. "Well, then, let's go," he says.

"That chair you're seated in is moving," he warns. "You're on the Futurama Ride . . . and look! You're down beneath the sea where industry thrives and where people work in comfort and safety. Now you go . . . into outer space. Quiet. It's so quiet, just as you knew it would be. And so peaceful."

Something drops on the page. It is a tear. Just one.

I realize that I have an unused pool of these. An avenue of fears. An exhibit of regrets.

I can't decide if I can put down my book. Is the World's Fair finished? No, it's alive.

Vast forces. Man's work.

Philosophy. Life. Knowledge. Power.

Solutions are everywhere at the fair. Nothing is unreachable.

I, for one, am staying on.

Peter Mandel is an author of books for children, including "Jackhammer Sam" (Macmillan), "Bun, Onion, Burger" (Simon & Schuster), and "Zoo Ah-Choooo" (Holiday House)