THERE'S A MAN from Mars who occasionally parks his flying saucer on the roof and drops down for a chat. He likes to keep up with American politics. "I see by your paper that a congressman by the name of Rhodes from Arizona wants to cut taxes 30 per cent," he said the other day. "Mr. Rhodes says that he wants to show the country which party stands for a real tax cut, and which one is the party of wild spending," the man from Mars went on. We agreed that Mr. Rhodes's intentions seem to lie in exactly that direction.

"Now, the last time I was here," said the Martian, "you explained to me that the Republicans are the party of low taxes, balanced budgets and self-reliance, which means letting people spend their own money instead of having the government spend it for them. They also favor business prosperity, and a strong national defense." We said that Mr. Rhodes himself couldn't have put it more precisely.

"Coming in on the saucer," he said, "I was looking at those government statistics you gave me the last time I was here. I remember that you told me the White House went from one party to the other in 1969, and went the other way in 1977. But I've forgotten which party was in power from 1969 to 1977."

"You can figure it out," we suggested. "You know the parties' policies, and you know what happened to the economy. Put it together.

The Martian poked for a moment through the tables at the back of the Economic Report, and said: "The really striking thing about your federal budgets from 1969 to 1977 is that they rose like rockets. They rose much faster than your economy as a whole. You must have been in the hands of the big spenders. Taxes didn't go up as fast as incomes, but they went up. I see that you slid into big recession in 1974-75, and you used the biggest budget deficit in your peacetime history to pull out of it. The government must have been run by those people you call the Keynesians - the deficit spenders." We acknowledged the truth, and told him to take a look at defense.

"Defense spending, when you take out inflation, drops steadily after the 1968 election and starts to turn around only with the 1977 budget," said the man from Mars. "Now it's rising quite fast." We pointed out that the country had been winding down a war in the early 1970s.

"Yes," said the Martian, "but those defense cuts weren't passed back to the public in lower taxes. Instead, direct government payments to individuals increased at the faster rate in all of your history. Social Security, mdeical care, welfare benefits, all those various entitlements - why, by 1977 just about half of your federal budget wa a huge insurance operation paying monthly checks to tens of millions of people." We told him to take a look at the figures on business profits.

"Terrible," said the man from Mars. "When you discount inflation, you see that corporate profits were lower in 1977 than in 1969, although the economy had grown by one-third. Speaking of inflation, by the end of the last administration you were in the worst inflation you've ever experienced. Also, the dollar had been devalued twice. The party is power during those years must have given a pretty low priority to a sound and stable currency."

All true, we ruefully conceded. Then we asked him to put it all together, and tell us who was in the White House during those years from 1969 to 1977.

"The Democrats, obviously," he said. "But there was a change last year, so now the Republicans must be in and your republic is safe again."

"You've got it exactly right," we said.