The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design.

The man of system, on the contrary, is apt to be very wise in
his own conceit; and is often so enamoured with the supposed
beauty of his own ideal plan of government, that he cannot suffer
the smallest deviation from any part of it. He goes on to
establish it completely and in all its parts, without any regard
either to the great interests, or to the strong prejudices which
may oppose it. He seems to imagine that he can arrange the
different members of a great society with as much ease as the
hand arranges the different pieces upon a chess-board. He does
not consider that the pieces upon the chess-board have no other
principle of motion besides that which the hand impresses upon
them; but that, in the great chess-board of human society, every
single piece has a principle of motion of its own, altogether
different from that which the legislature might chuse to impress
upon it. If those two principles coincide and act in the same
direction, the game of human society will go on easily and
harmoniously, and is very likely to be happy and successful. If
they are opposite or different, the game will go on miserably,
and the society must be at all times in the highest degree of
disorder.