In a sense, all of us are immigrants. Our roots go back beyond the water; our fathers, or our ultimate great-grandfathers, once took the long chance, got on a ship, and came to the New World. So what comes of it all? What sort of nation do we have, how has the fact that our roots go beyond the sea affected what has been done in this country?

It is always good to get a fresh point of view, and this is provided by Mr. Frank Thistlethwaite, a certified Cambridge don, in his new book The Great Experiment , which is a concise and neatly written attempt to explain the bewildering United States to English readers. It may also have the useful function of helping to explain us to ourselves.

The British, says Mr. Thistlethwaite, entertain odd misconceptions about America. They suspect that it is still a branch of Europe; they believe that it will presently accept this fact, drift around somehow to a British parliamentary government, and in other ways will behave as proper children of northwestern Europe ought to behave. The British want to know, mostly, “Why do Americans regard themselves as a special sort of people?” In this book Mr. Thistlethwaite undertakes to explain matters.

The Great Experiment: An Introduction to the History of the American People , by Frank Thistlethwaite. Cambridge University Press. 335 pp. $5.

One set of influences, he believes, has dominated American development—the influences that come from migration. These have brought about on our shores “a new variant of western society.” All of us have been uprooted; consequently, despite the cultural heritage we have brought with us, we developed an entirely new set of values. There is a deep psychological contrast. The American version of Western society is something new, which Mr. Thistlethwaite defines, quite simply, as “the mobile society.”

It is mobile in that nothing stays fixed. The act of immigration meant a rejection of custom. “In a sense,” says Mr. Thistlethwaite, “each new immigrant arriving at Castle Garden was already more American than the native-born son of the Republic in that he himself had shown the will to make a clean break with the past.” He was coming to the land where anything goes.

Nothing stayed fixed, and so the western frontier finally vanished, and then unrestricted immigration itself came to an end. But the mobility remained; for just as the forces which might have created a static society became dominant, the great catalyst of mass production appeared, offering a new frontier in an undiscovered dimension. It intensified the drive that the old frontier situation had begun; the mobility which conditioned American growth during the period of the great migration was extended; and so, says Mr. Thistlethwaite, “the social compulsions of the caravan have continued in important ways to govern American habit.”