In that case you will have to come here once more, and then, my good friend, we will see what can be done towards getting you safely home again." Israel was pouring out torrents of thanks when the Doctor interrupted him.
"Gratitude, my friend, cannot be too much towards God, but towards man, it should be limited.

No man can possibly so serve his fellow, as to merit unbounded gratitude.

Over gratitude in the helped person, is apt to breed vanity or arrogance in the helping one.

Now in assisting you to get home--if indeed I shall prove able to do so--I shall be simply doing part of my official duty as agent of our common country.

So you owe me just nothing at all, but the sum of these coins I put in your hand just now.