This section is from the book "Fly Fishing", by Sir Edward Grey. Also available from Amazon: Fly Fishing.
It follows from what has been said that every inch of water should be fished with as straight a line as possible; in still water this is not difficult; in fishing across and down stream it is easy, except in rough broken water, or where the stream is uneven, in which cases a line, which was cast straight, may do all sorts of curious things in the water, and the flies turn out to be in unexpected places ; in fishing up stream great care is always needed to prevent the line becoming slack. Here is another difficulty, for assuming that a fairly skilful dry fly angler can throw his wet flies lightly and accurately with a straight line, the management of the line in the water will still be unfamiliar to him. The art of keeping in touch with his flies in rough water is not learnt by the angler in chalk streams. In wet fly fishing, if the line becomes slack, the flies will sink deeper in the water. There is then less chance of seeing the rise of the fish, and the probability is that any trout, which takes the fly, will not be hooked or even felt when the line is slack. At the end of a day's fishing we know of the fish that have been touched or risen, but who can say how many trout have taken the fly and rejected it, unfelt and unseen ? Here therefore is another piece of skill required besides that of striking quickly, namely, that of keeping in constant touch with the fly without interfering with its motion in the stream. This is essential to success, but not easy to attain. In still water no doubt a motion must be given to the flies by movement of the hand, but except in still water and in very slow streams it is probably better to let the flies float down and sweep round with such movement as the stream may give them. So much for two respects in which a wet fly angler must be especially skilful to be very successful. He can only acquire this skill by long experience, and my own opinion is, that he can only maintain it by constant practice.
To this must be added, amongst other qualities, a knowledge of the habits of trout living in strong and rocky rivers with streams and pools and shallows. The biggest trout live in deep water, but it is not there that they will be caught with fly in the best of the fly fishing season. In a good day in April or May, trout, which are well on the feed, move up to the shallower broken water near the head of a pool, or to the wide rippling shallows, and it is in water knee deep, or even less, that not only more trout but the best trout will be caught.
Let us take an April day on some northern river. It is a day's fishing that is before us, and the first thought in the morning has been " what sort of a day is it ?" Probably that is the first thought of every one who lives out of a town and cares about the country. It is always some sort of a day in the country, not always the sort that has been expected or desired, but one to be looked at, studied, recognised and made the most of in an appropriate spirit. Now and then, but very rarely, there comes a day which is fit for nothing but to sit in the library with one's back to the window. I am sure I have known one or two such days, but I cannot describe one of them. Directly one begins to think of any past day, some feature of weather or light or sky is recalled, which seems to prove that the day had some interest, if only by contrast. The least interesting day is perhaps one with a dull unbroken sky, a very cold but not very strong east wind, the thermometer ranging only from about 32° to 350 in the twenty-four hours, and with neither sun, nor rain, nor snow, nor hail, nor frost, nor indeed anything violent or remarkable. As for great gales and storms there is a fearful joy and excitement about them not to be missed in the country, and rain is delightful. But the day that I am remembering now is a fine April day—one of the very best. April is not a warm month, but it has some warm days, and if an angler, who cannot fish all through the month, happens to choose these days for fishing, he ought to count himself a fortunate man. Such days may come at any time of the month, in the beginning, middle, or end, but in the north, at any rate before quite the end of April, trees will still be brown and bare. That does not matter. There will be a spirit in the air, an appeal, a promise, a prophecy, to make a man's heart leap up within him. There is a feeling of rising sap and reviving life. It is as if by some great effort of sympathy, a new sense had been discovered within us, such as has been imagined for fairies.
" Fairy ears a-listening, Hear the buds sprout in the spring, And for music to their dance Hear the hedgerows wake from trance ; Sap that trembles into buds, Sending little rhythmic floods Of fairy sound in fairy ears. Thus all beauty that appears Has birth as sound to finer sense And lighter clad intelligence".
This sense alone would be enough, but there are outward and visible signs too. Green is rising from the earth, and in some places is as high as the tops of shrubs. There are scents in the air and sounds of birds' songs; not the delicate songs of summer warblers, at any rate not in any quantity, but the more robust songs of birds which have spent the winter in the British Islands, and know the difference between the winter and the spring. On such a day in early April these birds will sing as if this were the day for which they had longed and waited, as if the highest bliss had come. Though some of our feeling about the conscious enjoyment of birds and other forms of life may be mere fancy, it is altogether true that there is an ecstasy about the first warm days of spring which cannot be resisted, and we cannot tell how much comes from within and how much from without us. There is a spirit stirring abroad. We know that we share it, and that it is not ours alone. This is what may be felt on the way to the river, knowing that the day is all before us and that all the day is ours. Time was when, eager to begin to fish, I used to hurry this part of the day, but that was a wasteful and irreverent habit. Fishing is to be enjoyed, but it will not be enjoyed any the more by hurrying past what Nature has to give us on the way. There is no need to hurry, for if the start is made in proper time, the rise will not have begun before the water is reached. On the bank the first thing noticed is the height and colour of the river, two things which are taken for granted on chalk streams, but which vary very greatly on northern rivers, and make a great difference not only to the result, but to the method of fishing.
 
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