I have formulated a rule for myself which I call the principle of the worst piece:"In positions of strategic manoeuvring (where time is not of decisive importance) seek the worst-placed piece. Activating that piece is often the most reliable way of improving your position as a whole."
"In the eighteenth century they announced their first rule: "Sortez les pieces" - "Get the pieces out". "It took a hundred years before a new rule was announced. Anderssen, the winner of the first International Tournament, that of London, 1851, said:
"Move that one of your pieces, which is in the worst plight, unless you can satisfy yourself that you can derive immediate advantage by an attack"
"A few decades went by [...] the masters evolved a "public opinion":
LASKER, Manual of Chess (second book)