Then Tom went on down, for he was afraid of staying near Grimes; and as he went, all the vale looked sad. The red and yellow leaves showered down into the river; the flies and beetles were all dead and gone; the chill autumn fog lay low upon the hills, and sometimes spread itself so thickly on the river that he could not see his way. But he felt his way instead, following the flow of the stream, day after day, past great bridges, past boats and barges, past the great town, with its wharfs, and mills, and tall smoking chimneys, and ships which rode at anchor in the stream; and now and then he ran against their hawsers, and wondered what they were, and peeped out, and saw the sailors lolling on board smoking their pipes; and ducked under again, for he was terribly afraid of being caught by man and turned into a chimney-sweep once more. He did not know that the fairies were close to him always, shutting the sailors' eyes lest they should see him, and turning him aside from millraces, and sewer mouths, and all foul and dangerous things. Poor little fellow, it was a dreary journey for him; and more than once he longed to be back in Vendale, playing with the trout in the bright summer sun. But it could not be. What has been once can never come over again. And people can be little babies, even water babies, only once in their lives. Besides, people who make up their minds to go and see the world, as Tom did, must needs find it a weary journey. Lucky for them if they do not lose heart and stop halfway, instead of going on bravely to the end as Tom did. For then they will remain neither boys nor men, neither fish, flesh, nor good red herring; having learnt a great deal too much, and yet not enough; and sown their wild oats, without having the advantage of reaping them. But Tom was always a brave, determined little English bulldog, who never knew when he was beaten; and on and on he held, till he saw a long way off the red buoy through the fog. And then he found, to his surprise, the stream turned round, and running up inland. It was the tide, of course; but Tom knew nothing of the tide. He only knew that in a minute more the water, which had been fresh, turned salt all round him. And then there came a change over him. He felt as strong, and light, and fresh, as if his veins had run champagne; and gave, he did not know why, three skips out of the water, a yard high, and head over heels, just as the salmon do when they first touch the noble, rich salt water, which, as some wise men tell us, is the mother of all living things.