It was doubtful how far the children believed his stories; probably, not having acquired the habit of examining evidence, they were content to accept ideas that threw a pleasant glamour on life.  But the coming of Jimmy Simpson altered this agreeable condition of mind.  Jimmy was one of those masterful stupid boys who excel at games and physical contests, and triumph over intellectual problems by sheer braggart ignorance.  From the first he regarded George with contempt, and when he heard him telling his stories he did not conceal his disbelief.

“It’s a lie,” he said; “there ain’t no fish in the tank.”

“I have seen it, I tell you,” said George.

Jimmy spat on the asphalt rudely.

“I bet no one else has,” he said.

George looked round his audience, but their eyes did not meet his.  They felt that they might have been mistaken in believing that they had seen the tail of the fish.  And Jimmy was a very good man with his fists.  “Liar!” said Jimmy at last triumphantly, and walked away.  Being masterful, he led the others with him, and George brooded by the tank for the rest of the evening in solitude.

Next day George went up to Jimmy confidently.  “I was right about the fish,” he said.  “I dreamed about it last night.”

“Rot!” said Jimmy; “dreams are only made-up things; they don’t mean anything.”

George crept away sadly.  How could he convince such a man?  All day long he worried over the problem, and he woke up in the middle of the night with it throbbing in his brain.  And suddenly, as he lay in his bed, doubt came to him.  Supposing he had been wrong, supposing he had never seen the fish at all?  This was not to be borne.  He crept quietly out of the flat, and tiptoed upstairs to the roof.  The stone was very cold to his feet.

There were so many things in the tank that at first, George could not see the fish, but at last he saw it gleaming below the moon and the stars, larger and even more beautiful than he had said.  “I knew I was right,” he whispered, as he crept back to bed.  In the morning he was very ill.

Meanwhile blue day succeeded blue day, and while the water grew lower in the tank, the children, with Jimmy for leader, had almost forgotten the boy who had told them stories.  Now and again one or other of them would say that George was very, very ill, and then they would go on with their game.  No one looked in the tank now that they knew there was nothing in it, till it occurred one day to Jimmy that the dry weather should have brought final confirmation of his scepticism.  Leaving his comrades at the long jump, he went to George’s neglected corner and peeped into the tank.  Sure enough it was almost dry, and, he nearly shouted with surprise, in the shallow pool of sooty water there lay a large fish, dead, but still gleaming with rainbow colours.

Jimmy was strong and stupid, but not ill-natured, and, recalling George’s illness, it occurred to him that it would be a decent thing to go and tell him he was right.  He ran downstairs and knocked on the door of the flat where George lived.  George’s big sister opened it, but the boy was too excited to see that her eyes were wet.  “Oh, miss,” he said breathlessly, “tell George he was right about the fish.  I’ve seen it myself!”