… is from pages 368-369 of Albert Venn Dicey’s monumental 1905 study, Lectures on the Relation Between Law & Public Opinion in England During the Nineteenth Century :
Parliament in most instances pays little regard to any general principle whatever, but attempts to meet in the easiest and most off-hand manner some particular grievance or want. Parliament is guided not by considerations of logic but by the pressure which powerful bodies can bring to bear upon its action.
Few summaries of the core conclusion of what only many years later was formalized as public-choice analysis  are as good as this one. And in light of the reality that Dicey here described so well (way back in 1905!), it’s especially discouraging that so many people today fall for the myth that government officials often, if not always, are philosopher kings who, unlike persons operating under the constraints and incentives created by private-property markets, are unusually willing and able to take the long-run view. The truth, of course, is that elected officials almost never even glance past the next election and are concerned overwhelmingly with maximizing their own chances of reelection.
People who put their faith in politicians to improve the world are no more reality-based or rational than are people who put their faith in rain-dancers to end droughts or in crystals to cure cancer.