RACHEL CARSON is remembered as an environmental pioneer, a scientist/naturalist/writer who was far ahead of her time. She died in 1964, two years after her book ''Silent Spring'' crusaded against DDT and other pesticides that were being used with deadly abandon.
Yet the most influential work of Carson's career could be an essay that first appeared in ''Woman's Home Companion.'' It came out as a book, ''The Sense of Wonder,'' in 1956, and has been published in a couple of different versions since then. The latest, available through The Nature Company, is $19.95.
Every adult who cares about a child should beg, borrow or buy a copy. The edition I have was published by Harper & Row in 1984 and can be found at most area libraries. It is a wise and eloquent book about seeing nature through a child's eyes, and Carson's advice to adults is priceless. Here's a favorite excerpt:
''A child's world is fresh and new and beautiful, full of wonder and excitement. It is our misfortune that for most of us that clear-eyed vision, that true instinct for what is beautiful and awe-inspiring, is dimmed and even lost before we reach adulthood.
''If I had influence with the good fairy who is supposed to preside over the christening of all children I should ask that her gift to each child in the world be a sense of wonder so indestructible that it would last throughout life, as an unfailing antidote against the boredom and disenchantment of later years, the sterile preoccupation with things that are artificial, the alienation from the sources of our strength.
''If a child is to keep alive his inborn sense of wonder without any such gift from the fairies, he needs the companionship of at least one adult who can share it, rediscovering with him the joy, excitement and mystery of the world we live in.''
It only takes a couple of minutes to go out and lie on your back in the grass, watching the clouds roll by. Let a kid be your guide. And if you get hooked, here are a few more books to help keep that sense of wonder alive.
* ''Sharing the Joy of Nature,'' by Joseph Cornell (Dawn Publications, $9.95, all ages; to order call 1-800-545-7475). This is the sequel to ''Sharing Nature with Children,'' and Cornell again proves to be full of practical advice and inventive ideas for turning folks on to nature.
The book is packed with games and activities geared to different age groups, many of which involve acting out the parts of animals (and, in a couple of instances, trees) in an energetic exploration of how the natural world works.
For rainy days, there's ''nature bingo'' or the animal clue game. And Cornell encourages the simple pleasures of a barefoot walk or time spent reading the works of John Muir, Rachel Carson and others listed in the back of the book.
* For more inspiration, check out ''Brother Eagle, Sister Sky: A Message from Chief Seattle,'' by Susan Jeffers (Dial, $14.95, all ages). Now that the earth is probably beyond repair, it's eerie to read the warning Chief Seattle issued almost 150 years ago, when the U.S. government first wanted to buy the lands inhabited by his Northwest Indian nation.
''The destiny of your people is a mystery to us,'' Chief Seattle said. ''What will happen when the buffalo are all slaughtered? The wild horses tamed? What will happen when the secret corners of the forest are heavy with the scent of many men?
''. . . And what will happen when we say good-bye to the swift pony and the hunt? It will be the end of living, and the beginning of survival.''
Jeffers' exquisite paintings span the pages like murals, and she uses a fine-line pen with ink and dyes to bring the landscapes alive with crosshatch texture.