[My research] throve best under adversity … in Germany in the middle 1930s under the Nazis when things became quite unpleasant and official seminars became dull. … We had a little private club… theoretical physicists and biologists. The discussions we had at that time have had a remarkable long-range effect, an effect that astonished us all. This was one adverse situation. Like the great Plague in Florence in 1348, which is the background setting for Bocaccio's Decameron.

But how is one to determine what is pleasing to God? ... Whatever is unpleasant to man is pleasant to God. The test is the natural instinct of man. If there arises within one’s dark recesses a hot desire to do this or that, then it is the paramount duty of a Christian to avoid doing this or that. And if, on the contrary, one cherishes an abhorrence of the business, then one must tackle it forthwith, all the time shouting ‘Hallelujah!’ A simple enough religion, surely–simple, satisfying and idiotic.

Mathematics has beauties of its own—a symmetry and proportion in its results, a lack of superfluity, an exact adaptation of means to ends, which is exceedingly remarkable and to be found only in the works of the greatest beauty. … When this subject is properly and concretely presented, the mental emotion should be that of enjoyment of beauty, not that of repulsion from the ugly and the unpleasant.

Men ought to know that from the brain, and from the brain only, arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs and tears. Through it, in particular, we think, see, hear, and distinguish the ugly from the beautiful, the bad from the good, the pleasant from the unpleasant, in some cases using custom as a test, in others perceiving them from their utility. It is the same thing which makes us mad or delirious, inspires us with dread or fear, whether by night or by day, brings sleeplessness, inopportune mistakes, aimless anxieties, absent-mindedness, and acts that are contrary to habit. These things that we suffer all come from the brain, when it is not healthy, but becomes abnormally hot, cold, moist, or dry, or suffers any other unnatural affection to which it was not accustomed. Madness comes from its moistness.

Only to often on meeting scientific men, even those of genuine distiction, one finds that they are dull fellows and very stupid. They know one thing to excess; they know nothing else. Pursuing facts too doggedly and unimaginatively, they miss all the charming things that are not facts. ... Too much learning, like too little learning, is an unpleasant and dangerous thing.

Some men said the atomic bomb should never have been built; researchers should have stopped working when they had realized that the bomb was feasible. Enrico did not think this would have been a sensible solution. It is no good trying to stop knowledge from going forward. Whatever Nature has in store for mankind, unpleasant as it may be, men must accept, for ignorance is never better than knowledge.
Note: Although attributed as his viewpoint to Enrico Fermi, it is probably not a direct quote by him.

Sometimes the very best way to deal with unpleasant things is to depict them in ways that allow people to laugh at them and destroy the power of unsayable things, rather than refusing to acknowledge them.

The history of science should not be an instrument to defend any kind of social or philosophic theory; it should be used only for its own purpose, to illustrate impartially the working of reason against unreason, the gradual unfolding of truth, in all its forms, whether pleasant or unpleasant, useful of useless, welcome or unwelcome.

The power that produced Man when the monkey was not up to the mark, can produce a higher creature than Man if Man does not come up to the mark. What it means is that if Man is to be saved, Man must save himself. There seems no compelling reason why he should be saved. He is by no means an ideal creature. At his present best many of his ways are so unpleasant that they are unmentionable in polite society, and so painful that he is compelled to pretend that pain is often a good. Nature holds no brief for the human experiment: it must stand or fall by its results. If Man will not serve, Nature will try another experiment.

There are no mistakes. The events we bring upon ourselves, no matter how unpleasant, are necessary in order to learn what we need to learn; whatever steps we take, they're necessary to reach the places we've chosen to go.

There are some arts which to those that possess them are painful, but to those that use them are helpful, a common good to laymen, but to those that practise them grievous. Of such arts there is one which the Greeks call medicine. For the medical man sees terrible sights, touches unpleasant things, and the misfortunes of others bring a harvest of sorrows that are peculiarly his; but the sick by means of the art rid themselves of the worst of evils, disease, suffering, pain and death.

Through seven figures come sensations for a man; there is hearing for sounds, sight for the visible, nostril for smell, tongue for pleasant or unpleasant tastes, mouth for speech, body for touch, passages outwards and inwards for hot or cold breath. Through these come knowledge or lack of it.

To master anything—from football to relativity—requires effort. But it does not require unpleasant effort, drudgery.

To most of us nothing is so invisible as an unpleasant truth. Though it is held before our eyes, pushed under our noses, rammed down our throats- we know it not.

Work is of two kinds: first, altering the position of matter at or near the earth’s surface relative to other such matter; second, telling other people to do so. The first kind is unpleasant and ill paid; the second is pleasant and highly paid.