For many centuries and in many countries the name Paradise was applied to pleasure gardens, according to Ronald Kent, who for 17 years was secretary of the Royal Botanic Gardens at Kew, in England. Not only are they beautiful but they display wealth, symbolize religious beliefs, contrast order and wilderness and always provide pleasure, he says.

Kent is the author of a beautiful new book, "The Quest for Paradise - A History of the World's Gardens" published by Mayflower Books (288 pages, $19.95 until Jan. 1, 1980, thereafter $24.95.)

There are hundreds of pictures in full color of many of the most famous gardens in the world plus an introduction by Anthony Huxley, author of many garden books including "Plant and Planet," a major botanical work, and "An Illustrated History of Gardening."

The author ranges from the Garden of Eden, through the beginnings of ornamental gardening in the first civilizations of Southwest Asia with the Hanging Gardens of Babylon, to the garden of China and Japan, to the nymph-haunted gardens of classical Greece and Rome.

Included are the cool fountains of the Persian paradise garden which, taken up by Islam, spread from Spain to India; the splendid Italian gardens of the Renaissance, the 17th-century French gardens of Le Notre, and the English gardens of the 18th century copied by all Europe.

The Victorian flower garden flares into life with new plants, and across the world the art of gardening achieves new glory in America.

The author describes the creators of these gardens and the plants they loved, from the sacred lotus of the Egyptians, the roses of the Persians and the cypresses of Italy to the cherry blossoms of Japan.

This glimpse into other people's gardens often becomes an insight into their lives, Kent says, as well as the principles of those who made them and the manners of those who enjoyed them, the plants they contained and the influence of newly discovered plants on garden design, the effects of climate, economy, culture and architecture.

Such insight opens up new possibilities of how a garden could and should be, he says.

From their wide reputation, there seems little doubt that the Hanging Gardens of Babylon were a magnificent set of terrace gardens, worthy of the great capital city they adorned.

The Bible establishes that the Hebrews possessed the same love of gardens that distinguished their neighbors. From early times their great men were buried in garden surroundings and from stories such as that of Susannah some idea can be gained of the gardens to which they were accustomed. Her adventure took place in a garden in Babylon during the exile, when oaks and mastic trees (Pistacia lentiscus) grew around a pool. The Hebrews' love of gardens is also evident from the Song of Solomon, probably the most sensuous and beautiful mystical poem written in any language.

A knowledgeable gardener interested in plants might be aware that some of his best-loved plants originated in Japan.

The Japanese are a people of extreme sensitivity of spirit, Kent says, and their ideas of the beautiful are precise. Something of those ideas must be understood before Japanese gardens can be appreciated.

Persian rugs and carpets are well known in Rome, but by the time King Chosroes' great carpet was made the Roman Empire in the West had gone down into darkess under the attacks of the barbarians. There were doubtless many beautiful gardens around the palaces of the emperor and the nobles, but although such gardens are mentioned many times in romances they are never described, so nothing is known about them.

It is perhaps at the Alhambra in Granada that the Moorish atmosphere may be felt most strongly because it is there that the remaining Moorish gardens are so closely integrated with the buildings that they are architecturally one. The finest and most important is the Court of the Myrtles, so called because of its myrtle hedges.

The great American love for gardens began in the early pioneering days, but had to wait until more settled times before it could swell into the great national passion that it is today.

Over a great part of Russia, the winter climate, as in Scandinavia and Canada, makes gardening difficult.

The author raises questions that concern all gardeners who breed new varieties of ornamental garden plants. Every year the flowers available for planting become showier, the blooms larger and the colors brighter or more bizarre as the breeders produce more varieties. An observer from another planet, or even a Japanese gardener, may question what intrinsic value there is in all this effort, apart from making money for the worthy breeders.

Why is a blue rose - not yet achieved but supposed to be the ultimate aim of rose breeders - so desirable, the author questions. There are already many beautiful flowers in all shades of blue. Why is a new and larger flower of any species to be preferred to the original? At camellia shows flowers detached from the plant are laid out in rows for comparison. It is hard to think of anything more unrelated to the marvelous beauty of a camellia flower nestling among the glossy, dark green foliage of its parent plant. Gardeners have been brainwashed to expect continual changes and to regard size and striking color or combinations of colors as the main criteria by which to judge a plant. These are crude values, surely. There are, of course, many discerning gardeners not influenced by this state of affairs, but they are in a small minority.