In the department of economy, an act, a habit, an institution, a law, gives birth not only to an effect, but to a series of effects. Of these effects, the first only is immediate; it manifests itself simultaneously with its cause -- it is seen. The others unfold in succession -- they are not seen: it is well for us, if they are foreseen. Between a good and a bad economist this constitutes the whole difference -- the one takes account of the visible effect; the other takes account both of the effects which are seen, and also of those which it is necessary to foresee. Now this difference is enormous, for it almost always happens that when the immediate consequence is favourable, the ultimate consequences are fatal, and the converse. Hence it follows that the bad economist pursues a small present good, which will be followed by a great evil to come, while the true economist pursues a great good to come, -- at the risk of a small present evil.

In fact, it is the same in the science of health, arts, and in that of morals. It often happens, that the sweeter the first fruit of a habit is, the more bitter are the consequences. Take, for example, debauchery, idleness, prodigality. When, therefore, a man absorbed in the effect which is seen has not yet learned to discern those which are not seen, he gives way to fatal habits, not only by inclination, but by calculation.

--From the introduction of Frederic Bastiat's "That Which is Seen, and That Which is Not Seen".