My friend, and my former teacher at NYU, Mario Rizzo read this recent post  and sent to me the following quotations from Herbert Spencer:
Evidence thrust  before us every morning shows throughout the body politic a fructifying causation so involved that not even the highest intelligence can anticipate the aggregate effects. The practical politician so-called, who thinks that the influences of his measure are to be shut up within the limits of the field he contemplates, is one of the wildest of theorists.
From Sec. 2.14 of “The Coming Slavery” in The Man versus the State :
The incident is recalled to me on contemplating the ideas of the so-called “practical” politician, into whose mind there enters no thought of such a thing as political momentum, still less of a political momentum which, instead of diminishing or remaining constant, increases. The theory on which he daily proceeds is that the change caused by his measure will stop where he intends it to stop. He contemplates intently the things his act will achieve, but thinks little of the remoter issues of the movement his act sets up, and still less its collateral issues.