On the contrary, says Eric Sayce, who lost his sight in his late fifties, after a successful career as an international salesman. "There are all these other factors. When you're walking, the exercise, the smells, the animal and bird sounds all make it a very enjoyable experience. If I want to examine a tree, I go up to it, put my arms round it and hug it. I can tell from the bark, and from the feel and smell of the leaves, what kind of a tree it is."
Eric has a splendid guide-dog, a German shepherd called Harry, who leads him unfailingly on routes that the pair of them have learned. But on any new trail in the country that Harry does not know, Eric needs a human guide, and prefers to walk holding one end of a white-painted broom-handle. As he says, "a sighted person gets the whole picture in a second. We have to build that picture block by block, using other senses."
To help in the process, a small charity has begun to pioneer the creation of audio cassettes for use outdoors. The Dog Rose Trust, based in Ludlow, was founded in 1996 by Julia Ionides, an architectural historian, and her husband Peter Howell, an architect. Until recently they concentrated on making high- quality recordings to guide blind people inside cathedrals and other historic buildings; now they are working on a project called "The Accessible Marches", which seeks to make the Shropshire countryside more rewarding to people who have sight problems. The aim of an interior recording is to capture acoustic ambience, which varies greatly from one part of a building to another, according to the height of the roof, the texture of the walls, the amount of glass, the floor covering, and so on. A commentary which reproduces all these differences accurately can give blind people a very vivid idea of their surroundings.
Outdoor recordings present greater problems. How do you capture the ambience of an open field? Yet, as Eric Sayce and many others testify, sounds are an enormous help. Birds singing, sheep bleating, wind in the leaves, water running over falls or rapids - all help to create images in the mind.
As part of their research, Julia and Peter went to the Downton Castle estate, near Ludlow, where, at the end of the 18th century, the antiquarian and collector Richard Payne Knight had himself built an acoustic walk. A path follows a stretch of river that contains many rapids, but as you move along it, a rising wall gradually blots out the sound. You then enter a man-made cave, where you cannot hear the river at all but, as you emerge at the other end, you pick up the full noise of the water again.
Valuable ideas emerged from Downton - as they did from an experimental visit to Shropshire made by members of Eric Sayce's group VISTA, the Visually Impaired and Sighted Tandem Association, who came over from Coventry, rode a dozen miles with a sighted pilot up front on each machine and a blind "stoker" helping with the power, then walked along a muddy trail and had lunch at the Plough, the pub- cum-brewery at Wistanstow.
Before the outing, several of the group were extremely nervous because they had not done much walking in the country and feared they might not manage; but at the end they were all exhilarated by their sense of achievement.
Now Julia is aiming to make tapes covering three walks in the spectacular hill country around Clun, Bishops Castle and Craven Arms. On a grey morning I walked out with her and Peter along one potential trail to the prehistoric stone circle known as Mitchell's Fold. Compared with Stonehenge or Avebury, the monument is modest, with only 15 medium-sized stones standing in a ring about 30 yards in diameter; yet its high, wild setting is infinitely more exciting than the downland of Wiltshire, and blind people would surely be stirred by a good description of it.
What else might a tape give them? Birdsong, for a start: skylarks were trilling away all around us, and pipits were cheeping as they flitted about the rough heather.
In a farm far down the valley a dog was barking. A recording might include an account of how the circle came to be built, three or four thousand years ago, and some speculation about its purpose. Was it the scene of ceremonial and ritual activities, and/or a bronze-age market place? Later history could mention the Mercian princes who used to rule here on the borders of Wales, and the lead-mining that flourished in the Middle Ages.
Another essential ingredient would be the folklore attached to the place. The central legend describes how a magic cow once gave milk to all the good people in the neighbourhood until a witch crept up and milked her into a sieve. The cow then vanished, but the witch was turned to stone, and a circle of other stones was built to keep her in. Semi-professional story-tellers, who abound in the area, could add further narratives, and local composers would contribute music inspired by the surroundings.
Research is needed into the best methods of using such a recording. Obviously, a blind person could listen to it before setting out on a walk, but it would have greater impact if tape or CD players were activated by radio signals from beacons deployed along the trail, so that when the carriers reached various points, they would hear descriptions of their immediate environs.
Tapes apart, the pioneers are talking to the Forestry Commission about the possibility of introducing Braille information boards and plates to put up on marker-posts - the tactile equivalent of the colour-coded posts that already mark many trails. Having been lucky enough to see the glorious country around Mitchell's Fold, I agree wholeheartedly with Julia and Peter when they say that blind people deserve all the help that a combination of imagination and technology can give them.
The Dog Rose Trust is at 83 Greenacres, Ludlow, Shropshire SY8 1LZ, Tel: 01584 874567