Henry David Thoreau says

We should consider that the flow of thought is more like a tidal wave than a prone river, and is the result of a celestial influence, not of any declivity in its channel. The river flows because it runs down hill, and flows the faster, the faster it descends. The reader who expects to float down stream for the whole voyage may well complain of nauseating swells and choppings of the sea when his frail shore-craft gets amidst the billows of the ocean stream, which flows as much to sun and moon as lesser streams to it. But if we would appreciate the flow that is in these books, we must expect to feel it rise from the page like an exhalation, and wash away our critical brains like burr millstones, flowing to higher levels above and behind ourselves.

There is many a book which ripples on like a freshet, and flows as glibly as a mill-stream sucking under a causeway; and when their authors are in the full tide of their discourse, Pythagoras and Plato and Jamblichus halt beside them. Their long, stringy, slimy sentences are of that consistency that they naturally flow and run together.

They read as if written for military men, for men of business, there is such a dispatch in them. Compared with these, the grave thinkers and philosophers seem not to have got their swaddling clothes off; they are slower than a Roman army in its march, the rear camping to-night where the van camped last night. The wise Jamblichus eddies and gleams like a watery slough.

How many thousands never heard the name
Of Sidney, or of Spenser, or their books!
And yet brave fellows, and presume of fame,
And seem to bear down all the world with looks.

The ready writer seizes the pen, and shouts, "Forward! Alamo and Fanning!" and after rolls the tide of war. The very walls and fences seem to travel. But the most rapid trot is no flow after all; and thither, reader, you and I, at least, will not follow.

A perfectly healthy sentence, it is true, is extremely rare. For the most part we miss the hue and fragrance of the thought; as if we could be satisfied with the dews of the morning or evening without their colors, or the heavens without their azure. The most attractive sentences are, perhaps, not the wisest, but the surest and roundest. They are spoken firmly and conclusively, as if the speaker had a right to know what he says, and if not wise, they have at least been well learned. Sir Walter Raleigh might well be studied, if only for the excellence of his style, for he is remarkable in the midst of so many masters. There is a natural emphasis in his style, like a man's tread, and a breathing space between the sentences, which the best of modern writing does not furnish. His chapters are like English parks, or say rather like a Western forest, where the larger growth keeps down the underwood, and one may ride on horseback through the openings. All the distinguished writers of that period possess a greater vigor and naturalness than the more modern--for it is allowed to slander our own time--and when we read a quotation from one of them in the midst of a modern author, we seem to have come suddenly upon a greener ground, a greater depth and strength of soil. It is as if a green bough were laid across the page, and we are refreshed as by the sight of fresh grass in midwinter or early spring. You have constantly the warrant of life and experience in what you read. The little that is said is eked out by implication of the much that was done. The sentences are verdurous and blooming as evergreen and flowers, because they are rooted in fact and experience, but our false and florid sentences have only the tints of flowers without their sap or roots. All men are really most attracted by the beauty of plain speech, and they even write in a florid style in imitation of this. They prefer to be misunderstood rather than to come short of its exuberance. Hussein Effendi praised the epistolary style of Ibrahim Pasha to the French traveler Botta, because of "the difficulty of understanding it; there was," he said, "but one person at Jidda who was capable of understanding and explaining the Pasha's correspondence." A man's whole life is taxed for the least thing well done. It is its net result. Every sentence is the result of a long probation. Where shall we look for standard English, but to the words of a standard man? The word which is best said came nearest to not being spoken at all, for it is cousin to a deed which the speaker could have better done. Nay, almost it must have taken the place of a deed by some urgent necessity, even by some misfortune, so that the truest writer will be some captive knight, after all. And perhaps the fates had such a design, when, having stored Raleigh so richly with the substance of life and experience, they made him a fast prisoner, and compelled him to make his words his deeds, and transfer to his expression the emphasis and sincerity of his action.