"I have an hour to spare," said the professor, pulling out his watch:
"perhaps, if you will bring me your book and slate, I can elucidate the
rule which is perplexing you."

"Oh, will you _really_?" she exclaimed, a radiant smile lighting up her
troubled face. "I'll bring them right away. How kind, how _very_ kind
you are, to bother with my sums, when you have so much Greek in your
head!" And, obeying an impulse, as she so often did, she caught his hand
in both her own and kissed it heartily. Then she skimmed across the
parlor, and he heard her child's voice "lilting lightly up the" stairs
as he stood--in a position suggestive of Mrs. Jarley's wax-works--gazing
fixedly at the hand which she had kissed.

"She regards me as a father," he said to himself severely. "Am I going
mad? Or becoming childish? No; I am only sixty. But, even if it were
possible, it would be base, unmanly, to take advantage of her
loneliness, her gratitude. No, I will be firm."

So, when the offending "example" was handed to him, with the
above-quoted touching statement as to its total depravity, he looked
only at the slate. Gently and patiently, as if to a little child, he
pointed out the errors and expounded the rule, amply rewarded by her
joyful exclamation, "Oh, I see _exactly_ how it's done, now! You do
explain things beautifully. I really think I could have learned a good
deal if I'd had a teacher like you when I went to school."

"Come to me whenever your lessons perplex you, my dear," he answered,
still looking at the slate; "come freely, as if--as if I were your
father."