THE trouble with Plymouth Rock is that we don't really know for sure that the Pilgrims landed there. But that's all right, because if they didn't land there literally, they did so metaphorically, which is more important.
This is one of the insights from a week's tour, with visiting kinfolk, of New England, a sort of Highlights of American History summer session. The contemporary accounts of the Pilgrims' landing - William Bradford's and the one known as ''Mourt's Relation'' - do not mention a specific rock as a landing place. But then Bradford doesn't even mention the Mayflower by name; it's just ''the Ship.'' And there are plenty of theories, embraced by such serious historians as Samuel Eliot Morison, as to how what we know as Plymouth Rock could indeed have been significant to the Pilgrams.
But the Rock acquired its celebrity status after 1741. That is when Elder Faunce, a 95-year-old Plymouth resident who as a boy had known Bradford, Miles Standish, John Alden, and others, heard of a plan to build a wharf over the rock.
This was the rock, he insisted, that his father ''had assured him was that which had received the footsteps of our fathers on their first arrival, and which should be perpetuated to posterity,'' according to Thacher's 1832 ''History of Plymouth.''
The venerable elder was carried to the shore in a chair; he pointed out the rock - the Rock - to the assembled company, and ''bedewed it with his tears, and bid to it an everlasting adieu.''
My source for all this, a Pilgrim Society publication called ''Plymouth Rock: History and Significance,'' by Rose T. Briggs, does not say that this emotional display prevented the wharf from being built. And in fact, the rock was to have a somewhat peripatetic existence over the next century or so. It split in two, for instance, during a 1774 attempt to consecrate it as a ''shrine of liberty'' on the eve of the Revolution; the fracture was seen as a bad omen for the British Empire.
By 1835, Alexis de Tocqueville observed, ''The Rock has become an object of veneration in the United States.... Here is a stone which the feet of a few outcasts press for an instant; and the stone becomes famous; it is treasured by a great nation; its very dust is shared as a relic.'' Today we may smile at the protective canopy, the work of no less an architectural firm than McKim, Mead and White, under which the Rock, its top and bottom sections reunited, rests; an earlier canopy was even more elaborate.
The Rock is a symbol of history, and the history of history, of 18th- and 19th-century Americans in love with their Pilgrim past - the depth of the religious and moral conviction of their forebears, their great courage, their commitment to democracy through the Mayflower Compact.
And that heritage still speaks to ordinary citizens today, albeit in less high-flown language than Daniel Webster might have used a century and a half ago. Aboard the Mayflower II, the replica of the original ship, I heard one tourist remark to another, ''You know how upset we get when we have a bad trip, get into a bad RV park or something? Can you imagine how these people might have groused to their relatives? 'What have you gotten us into?!' ''
Observing the cramped quarters aboard ship, or the primitive living conditions in Plimoth Plantation, a few miles up the road, one has to wonder, How would I have held up? Would I have made it?
Briggs notes that ''doubters wonder if the tale'' of the Rock is ''not too perfect poetry to be material fact.'' One can give complete credence to the accounts of Elder Faunce's pronouncements about the Rock and still entertain the thought that if it did not exist it would have been invented. And as Briggs concludes, ''It is not a bad thing for a nation to be founded on a rock.''
May every nation find the rock it needs.