When you have solved that problem of N to the fourth, I think you will see that we could really have done nothing else, because, if you once crossed the border-line--the horizon which Professor Cayley spoke of, I mean--you ought to be on speaking terms with them." Before he replied to this somewhat searching remark, the man who _had_ crossed the horizon emptied his coffee cup, and set it down in the saucer with a perceptible rattle.

Then he said more slowly than before: "My dear Niti, there are other mysteries than N to the fourth.

I only wish now to confess frankly to you that I have tried to solve one of them, perhaps the greatest of all, and ignominiously failed.

I learnt a great deal last night from a young man to whom I thought I could have taught anything, and I got up this morning in a distinctly chastened frame of mind; and so, to make a long story short, if you like to drive into town and bring Commander Merrill back to lunch, I shall be very pleased to have a chat with him afterwards." The next moment Nitocris was on the other side of the table, with her arm round her father's shoulders.

She kissed him, and whispered: "You dearest of dears! If I could have loved you any more, I would now, but I can't.