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.

50885    But the note itself.

50886    What do you deduce from it?'

50887    I carefully examined the writing, and the paper upon which it was written.

50888    'The man who wrote it was presumably well-to-do.' I remarked, endeavouring to imitate my companion's processes.

50889    'Such paper could not be bought under half a crown a packet.

50890    It is peculiarly strong and stiff.'

50891    'Peculiar - that is the very word,' said Holmes.

50892    'It is not an English paper at all.

50893    Hold it up to the light.'