IN THE LONG RUN, Mark Twain said, soap and education are dead. You could not prove his dictum to the people at Procter & Gamble these days, however - they who are bubbling over with patriotic enthusiasm about the 100-year anniversary of their miraculous soap. In fact, they are right to link the country's successes with their own. Ever since James N. Gamble boiled his magic kettle in Cincinnati in 1878, cleanliness has stayed right next to godliness, not to mention money, at Procter & Gamble; and the idea that rose to the top a century ago, floats just as well today.

Mr. Gamble may have been the one to discover the remarkable substance, but it was Mr. Proctor who made it divine. One Sunday morning in 1879, Mr. Procter sat in church when Psalm 45 was read. From the passage, "All my garments smell of myrrh, and aloes, and cassia, out of the ivory palaces, whereby they have made thee glad," came the inspiration to change the soap's name from P & G's White Soap to "Ivory." How posterity would have been altered had Mr. Procter favored "Myrrh" or "Cassia" is problemactical, but there was no doubt about "Ivory." The name meant a sure-fire American success, first of all because the soap worked and, a close second, because it brought to mind riches and purity - we need not repeat the exact percentage of purity - thereby enabling the sainted American housewife to hold all three worlds of function, profit and spirit in her wet little palm.

What she was also holding - although no once could be absolutely certain in 1879 - was a genuine American icon, one of the half dozen commercial products in our high technological history, like Coke and Ford, that have gained a sentimental, quasi-spiritual dimension on their way to the buck. In a country where commerce is sacred, goods are relics. Not even Marilyn Chambers, star of the X-rated "Behind the Green Door," who also starred in Ivory commercials, could soil the association of Ivory with virtue.