As you know, the Mediterranean Sea was once a desert, and of course everybody knows how to tell what minerals are to be found in virtually any star simply by consulting the user-friendly spectroscope, and how that works we all know. Most of us even know that if the Bible were printed on leaves of gold leaf, the entire volume would be no thicker than one paper page.

Even so, it was news to me that you can photograph a single atom, and as one who has always suspected that light is not some ethereal stuff but has weight, I am glad to have this suspicion confirmed in "Ring of Truth," a television series that begins tonight (at 9 p.m. on Channel 26 and Maryland Public Television stations).

In six hour-long sessions on subsequent Tuesdays, Philip and Phylis Morrison wander about the world demonstrating how science works, a highly agreeable jaunt that cost the Polaroid Corp. more than $2 million, a thing worth mentioning since I do not recall any tigers, bunny rabbits or dancing girls in it. It is not all that common, in other words, for businesses to pay for shows that will not reach vast audiences and that will not prey on national fears nor appease some lively pressure group.

The tiger-rabbit shows are sufficiently irresistible to stand on their own, but shows on physics need a little pump-priming, both at the sponsorship level and the show biz level. The demonstrator should be rather lively, wouldn't you say, if we are to watch?

Philip Morrison is a professor of physics at Massachusetts Institute of Technology who is said to have made vivid impressions on his students in the past 20 years, a thing not surprising in a scientist who has figured out that the average cyclist in the Tour de France race consumes the equivalent of 32 jelly doughnuts a day.

Neither he nor his wife is a buffoon, however, and he begins the show by telling us we have got to "pay attention." A little edge to the voice just there. A man, possibly, who has seen one too many cop-and-bimbo epics and who wonders if that's all there is.

Well, I paid attention, for the novelty of it all, and feel rewarded. Morrison (his wife does not do the lecturing, though in real life she has long taught in various fields) has greenish eyes with specks in them and a kind of triangular face suggesting both a quite young kitten and a manic Jack Russell terrier going to ground. He says "cosmos" to rhyme with "glucose" and accents the last syllable of "artisan." These are both allowable in those dictionaries that allow everything. But apart from this, he is a very gentle perfect teacher, friendly in authority, clear in speech and convincing about the jelly doughnuts.

It took the camera crews a while to get used to him. When he holds two lenses to show how a telescope works, the camera shoots them exactly as he holds them, and this is a great bother. The simple and usual way is to film the lens demonstration later, in the studio, with the lenses mounted. It is harder to shoot it in the middle of Venice with Morrison's fingers (surprisingly steady, by the way) as frame.

This insistence on truth, in the sense that what you think you are seeing is indeed what you are seeing -- no tricks anywhere in the show -- may not be worth the extra cost, but then truth rarely is. You can go over budget quite easily.

One reason so many of us are illiterate in science is that it is commonly explained in abstract terms. But when Morrison tells how stellar minerals are detected, he shows what is done to the telescope to break light into a spectrum, and shows how every mineral has a spectrum different from any other. How is this known? Morrison does not so much say as demonstrate.

He does not, alas, demonstrate the weight of light. We have such wretched scales to work with. I should ask him about the sun throwing all that light on the world for umpty years, whether that weight would not eventually add up and throw us out of orbit. He does not mind dumb questions. Or questions we do not usually think of. To him no questions are dumb. It's how we learn, Madge-baby. Or could.