What to observe

source

But it is in matters beyond the limits of mere rule that the skill of the analyst is evinced. He makes, in silence, a host of observations and inferences. So, perhaps, do his companions; and the difference in the extent of the information obtained, lies not so much in the validity of the inference as in the quality of the observation. The necessary knowledge is that of what to observe.

Edgar Allan Poe - The Murders in the Rue Morgue (1841)

What we observe and don't observe seems to be a fundamental difference between people and groups. It's an important point, but to my mind Poe's melodramatic story does it no favours as a valuable social comment.