The children were delighted till they remembered how they had once wished for wings themselves, and had had them--and then they felt how desperately unhappy anything with wings must be if it is shut up in a cage and not allowed to fly.
'It must be fairly beastly to be a bird in a cage,' said Cyril.

'Come on!' They went on, and Cyril tried to think out a scheme for making his fortune as a gold-digger at Klondyke, and then buying all the caged birds in the world and setting them free.

Then they came to a shop that sold cats, but the cats were in cages, and the children could not help wishing someone would buy all the cats and put them on hearthrugs, which are the proper places for cats.

And there was the dog-shop, and that was not a happy thing to look at either, because all the dogs were chained or caged, and all the dogs, big and little, looked at the four children with sad wistful eyes and wagged beseeching tails as if they were trying to say, 'Buy me! buy me! buy me! and let me go for a walk with you; oh, do buy me, and buy my poor brothers too! Do! do! do!' They almost said, 'Do! do! do!' plain to the ear, as they whined; all but one big Irish terrier, and he growled when Jane patted him.
'Grrrrr,' he seemed to say, as he looked at them from the back corner of his eye--'YOU won't buy me.

Nobody will--ever--I shall die chained up--and I don't know that I care how soon it is, either!' I don't know that the children would have understood all this, only once they had been in a besieged castle, so they knew how hateful it is to be kept in when you want to get out.
Of course they could not buy any of the dogs.