It is important to distinguish between complexity and clutter

The solving of crimes in particular - and the asking of questions of nature in general - requires the capacity to manage complexity.1 Too often, apparent complexity is simply clutter. There is, however, genuine complexity. Some systems have many elements with myriad relationships between them. It is important to remove the clutter of content, so that one can see clearly to put this content into context, in order to manage the genuine complexity.

I have, on a number of occasions likened my arch-rival, Professor Moriarty, to a spider at the centre of its web:

He sits motionless, like a spider in the centre of its web, but that web has a thousand radiations, and he knows well every quiver of each of them [FINA].
--- dozens of exiguous threads which lead vaguely up towards the centre of the web where the poisonous, motionless creature is lurking [VALL]
Watson uses a suspiciously similar metaphor for me, though he has the grace not to mention the spider:
He (me) loved to lie at the very centre of five millions of people, with his filaments stretching out and running through them, responsive to every little rumour or suspicion of unsolved crime [CARD].
It is in this capacity to manage complexity that the truly intelligent - like myself and my near-equal, Professor Moriarty - can be distinguished from the merely competent. Watson's favourite metaphor for detection as the unravelling of a ball of thread is obviously inadequate. We are dealing not with a linear thread but with a web or net, in which the various threads are tied together into a system.

1   Information overload is often described as the problem of the 1990s. I was well into a project on information overload, when I realized that it was a pseudo-problem. It is like looking at a magnificent smorgasbord and yelling "overload". It is overload only if you think you have to eat it all. In our outside-in educational system, we are convinced that being educated is assimilating information from our environment. Our modern environment is so rich in information that we despair. In an inside-out education system, we would be delighted to have such a rich environment to pull out more of the human potential. Underlying the pseudo-problem of information overload, however, there lies a genuine problem of the management of complexity. We have to develop a sophisticated, subtle subjective map to match this rich objective world. Since then, I have realized that my various intellectual strategies are different techniques for managing complexity.