50870    Now, I know that there are seventeen steps, because I have both seen and observed.

50871    By the way, since you are interested in these little problems, and since you are good enough to chronicle one or two of my trifling experiences, you may be interested in this.'

50872    He threw over a sheet of thick pink-tinted note-paper which had been lying open upon the table.

50873    'It came by the last post,' said he.

50874    'Read it aloud.'

50875    The note was undated, and without either signature or address.

50876    'There will call upon you to-night, at a quarter to eight o'clock,' it said, 'a gentleman who desires to consult you upon a matter of the very deepest moment.

50877    Your recent services to one of the Royal Houses of Europe have shown that you are one who may safely be trusted with matters which are of an importance which can hardly be exaggerated.

50878    This account of you we have from all quarters received.

50879    Be in your chamber then at that hour, and do not take it amiss if your visitor wear a mask.'

50880    'This is indeed a mystery,' I remarked.

50881    'What do you imagine that it means?'

50882    'I have no data yet.

50883    It is a capital mistake to theorise before one has data.

50884    Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.