I was talking recently with my friend @k_trinhy and I was relaying to her a profound categorization of people by a German Army general:

I divide my officers into four groups. There are clever, diligent, stupid, and lazy officers.

Usually two characteristics are combined.

Some are clever and diligent – their place is the General Staff.

The next lot are stupid and lazy – they make up 90 percent of every army and are suited to routine duties.

Anyone who is both clever and lazy is qualified for the highest leadership duties, because he possesses the intellectual clarity and the composure necessary for difficult decisions.

One must beware of anyone who is stupid and diligent – he must not be entrusted with any responsibility because he will always cause only mischief.

– Kurt von Hammerstein-Equord

Wikipedia source

This was the best system of categorizing people I have so far seen. 😄