‘Would it be afraid of catching cold?’ said Bruno.

      ‘If it got very damp,’ Sylvie suggested, ‘it might stick to something, you know.’

      ‘And that somefin would have to go by the post, what ever it was!’ Bruno eagerly exclaimed. ‘Suppose it was a cow! Wouldn’t it be dreadful for the other things!’

      ‘And all these things happened to him,’ said the Professor. ‘That’s what makes the song so interesting.’

      ‘He must have had a very curious life,’ said Sylvie.

      ‘You may say that!’ the Professor heartily rejoined.

      ‘Of course she may!’ cried Bruno.

      By this time we had come up to the Gardener, who was standing on one leg, as usual, and busily employed in watering a bed of flowers with an empty watering-can.

      ‘It hasn’t got no water in it!’ Bruno explained to him, pulling his sleeve to attract his attention.

      ‘It’s lighter to hold,’ said the Gardener. ‘A lot of water in it makes one’s arms ache.’ And he went on with his work, singing softly to himself

      ‘The nights are very damp!’

      ‘In digging things out of the ground—which you probably do now and then,’ the Professor began in a loud voice; ‘in making things into heaps—which no doubt you often do; and in kicking things about with one heel—which you seem never to leave off doing; have you ever happened to notice another Professor something like me, but different?’

      ‘Never!’ shouted the Gardener, so loudly and violently that we all drew back in alarm. ‘There ain’t such a thing!’

      ‘We will try a less exciting topic,’ the Professor mildly remarked to the children. ‘You were asking—’

      ‘We asked him to let us through the garden-door,’ said Sylvie: ‘but he wouldn’t: but perhaps he would for you!’

      The Professor put the request, very humbly and courteously.

      ‘I wouldn’t mind letting you out,’ said the Gardener. ‘But I mustn’t open the door for children. D’you think I’d disobey the Rules? Not for one-and-sixpence!’

      The Professor cautiously produced a couple of shillings.

      ‘That’ll do it!’ the Gardener shouted, as he hurled the watering-can across the flower-bed, and produced a handful of keys—one large one, and a number of small ones.

      ‘But look here, Professor dear!’ whispered Sylvie. ‘He needn’t open the door for us, at all. We can go out with you.’

      ‘True, dear child!’ the Professor thankfully replied, as he replaced the coins in his pocket. ‘That saves two shillings!’ And he took the children’s hands, that they might all go out together when the door was opened. This, however, did not seem a very likely event, though the Gardener patiently tried all the small keys, over and over again.

      At last the Professor ventured on a gentle suggestion. ‘Why not try the large one? I have often observed that a door unlocks much more nicely with its own key.’

      The very first trial of the large key proved a success: the Gardener opened the door, and held out his hand for the money.

      The Professor shook his head. ‘You are acting by Rule,’ he explained, ‘in opening the door for me. And now it’s open, we are going out by Rule—the Rule of Three.’

      The Gardener looked puzzled, and let us go out; but, as he locked the door behind us, we heard him singing thoughtfully to himself

      ‘He thought he saw a Garden-Door

      That opened with a key:

      He looked again, and found it was

      A Double Rule of Three:

      “And all its mystery,” he said,

      “Is clear as day to me!”’ [•]

      ‘I shall now return,’ said the Professor, when we had walked a few yards: ‘you see, it’s impossible to read here, for all my books are in the house.’

      But the children still kept fast hold of his hands. ‘Do come with us!’ Sylvie entreated with tears in her eyes.

      ‘Well, well!’ said the good-natured old man. ‘Perhaps I’ll come after you, some day soon. But I must go back now. You see I left off at a comma, and it’s so awkward not knowing how the sentence finishes! Besides, you’ve got to go through Dogland first, and I’m always a little nervous about dogs. But it’ll be quite easy to come, as soon as I’ve completed my new invention—for carrying one’s-self, you know. It wants just a little more working out.’

      ‘Wo’n’t that be very tiring, to carry yourself?’ Sylvie enquired.

      ‘Well, no, my child. You see, whatever fatigue one incurs by carrying, one saves by being carried! Good-bye, dears! Good-bye, Sir!’ he added to my intense surprise, giving my hand an affectionate squeeze.

      ‘Good-bye, Professor!’ I replied, but my voice sounded strange and far away, and the children took not the slightest notice of our farewell. Evidently they neither saw me nor heard me, as, with their arms lovingly twined round each other, they marched boldly on.