AN OLD and terrifying truth haunts the exhibition which goes on view today at the Freer Gallery of Art. "Chinese Art of the Warring States Period: Change and Continuity 480-222 B.C." summons restless ghosts. If you listen to its stillness you can almost hear them moan. Their blood drips from these slender swords, their silent screams surround these things of bronze and jade.

Most are delicately inlaid with threads of gold and silver. The 151 works of art displayed are so elegant in outline, so subtle in proportion, it is easy to forget the cruelty and violence of the people who produced them. Civilized they surely were. Civil they were not.

Harry Lime was right. Italy under the Borgias produced Michelangelo, Leonardo, and the glories of the Renaissance, while Switzerland, at peace, gave us but the cuckoo clock. Ceaseless war and butchery, in China as in Europe, were not enemies of art.

The Warring States Period well deserves its name. For 2 1/2 centuries, the armies of the court of Chou, and those raised by the states of Yen, Han, Chao and Wei, Ch'i, Ch'in and Ch'u, battled almost endlessly. Wei lost 60,000 men to Ch'in in 364 B.C. Some 60,000 Han soldiers died in 307 B.C. A battle even bloodier was fought between the armies of Chao and Ch'in in 260 B.C.

"Believing that they had been promised that their lives would be spared, the entire Chao army surrendered," writes the Freer's director, Thomas Lawton. "In an act of wanton savagery even for this period, the Ch'in slaughtered 450,000 Chao captives by burying them alive."

It must have been the worst of times. Yet little of its horror marks its works of art.

Some are delicate as dragon flies, none of them is crude. A number of the bronzes here, these plump, peculiar quadrupeds with big ears and small tails -- are they pigs or sheep or tapirs? -- might even be called cute.

"The Warring States Period," Lawton writes, "was an era of transition that might be described as the watershed between old and new China." The ancient feudal order of the Dynasty of Chou was falling into chaos when these things were made. Yet its dissolution saw a new and sumptuous beauty enter Chinese art.

Merchants assumed roles of power; new roads, canals and walls were built, and certain cities prospered. The streets of one of these, Lin-tzu, "were said to be so choked with chariots that hubcaps struck against one another, and pedestrians were so numerous that if they were all to wipe perspiration from their brows at once, a rainfall would result."

We do not know what music those city folk enjoyed, what dances entertained them, what sumptuous feasts they ate. The gorgeous silks they wore have long since decayed, but the beauty of their clothing is abundantly suggested by their garment hooks of silver, turquoise, gold and jade. Their chariots, too, were lovely. A bronze ornament from one of them -- a dragon head whose slender curving tongue is made of gilded silver -- is also on display.

The rulers of the Warring States were buried with great pomp. Their most beloved possessions, their vessels, mirrors, swords -- and their living, frightened horses, too -- joined them in the grave. That is the only reason these old objects have survived.

Because almost all of them were unearthed by grave robbers -- who passed them on to dealers who sold them to the Freer -- scholars here, for years, could do little more than guess at their sources and their dates. Nor could much be learned from the rare inscriptions on them. One of these, on the head of a bronze bird (which looks much like the Maltese Falcon), was translated eventually. It says: "The gentleman's esteemed bird."

Recently, however, scientific excavations conducted by Chinese archaeologists have produced much new information.

Two bronze fittings here, whose curving snakes are beautifully inlaid with gold and silver, were long described by scholars as "chariot decorations." A 1972 excavation has shown, however, that they are parts of a crossbow.

Five smaller bronzes were once catalogued as "longbow tips." Recent discoveries have shown them to be finials of the spines of an umbrella. A bronze hook was called, for years, "a garment hook." It was nothing of the kind. In 1979, two similar hooks were found beside a covered tripod in the grave of Marquis I of Tseng. "Apparently," writes Lawton, "hooks of this type were inserted through the open handles of bronze vessels to lift the tripods while they were still hot."

There are masterworks on view here. One of the most beautiful is a "pien-hu," or canteen, elaborately inlaid with still-shiny lines of silver. Its complex interweavings eerily recall the decorations on ancient Celtic art.

The Warring States Period ended in 221 B.C. when King Chien of the state of Chi was captured by the troops of Ch'in. The victor was, at last, able to proclaim himself Shih-huang-ti, the First Emperor of China. The show closes Feb. 15, 1983.