A person must have a very unusual taste for intellectual exercise in and for itself who will put himself to the trouble of thought when it is to have no outward effect, or qualify himself for functions which he has no chance of being allowed to exercise.
 John Stuart Mill, Considerations on Representative Government (1861). copy citation

Context

“and even under the most moderate of despots, none but persons of already admitted or reputed superiority could hope that their suggestions would be known to, much less regarded by, those who had the management of affairs. A person must have a very unusual taste for intellectual exercise in and for itself who will put himself to the trouble of thought when it is to have no outward effect, or qualify himself for functions which he has no chance of being allowed to exercise. The only sufficient incitement to mental exertion, in any but a few minds in a generation, is the prospect of some practical use to be made of its results. It does not follow that the nation will be wholly destitute of intellectual power.” source