Credo quia absurdam — I believe because it is absurd
The Tragic Sense of Life (1913), Conclusion : Don Quixote in the Contemporary European Tragi-Comedy

“"And the upshot of all this," so I have been told more than once and by more than one person, "will be simply that all you will succeed in doing will be to drive people to the wildest Catholicism." And I have been accused of being a reactionary and even a Jesuit. Be it so!… I know very well it is madness to seek to turn the waters of the river back to their source, and that it is only the ignorant who seek to find in the past a remedy for their present ills; but I know too that anyone who fights for any ideal whatever, although his ideal may seem to lie in the past, is driving the world on to the future, and that the only reactionaries are those who find themselves at home in the present. Every supposed restoration of the past is a creation of the future, and if the past which it is sought to restore is a dream, something imperfectly known, so much the better.”

Miguel de Unamuno

The Tragic Sense of Life (1913), Conclusion : Don Quixote in the Contemporary European Tragi-Comedy

“And above all, we must feel and act as if an endless continuation of our earthly life awaited us after death; and if it be that nothingness is the fate that awaits us we must not, in the words of Obermann, so act that it shall be a just fate.”

Miguel de Unamuno

The Tragic Sense of Life (1913), X : Religion, the Mythology of the Beyond and the Apocatastasis

“Just as eunuchs will never know aesthetics as applied to the selection of beautiful women, so neither will pure rationalists ever know ethics, nor will they ever succeed in defining happiness, for happiness is a thing that is lived and felt, not a thing that is reasoned or defined.”

Miguel de Unamuno

The Tragic Sense of Life (1913), V : The Rationalist Dissolution

“And what has Don Quixote left, do you ask? I answer, he has left himself, and a man, a living and eternal man, is worth all the theories and all the philosophies. Other peoples have left chiefly institutions, books; we have left souls; St. Teresa is worth any institution, any Critique of Pure Reason.”

Miguel de Unamuno

The Tragic Sense of Life (1913), Conclusion : Don Quixote in the Contemporary European Tragi-Comedy

“Reason perhaps teaches certain bourgeois virtues, but it does not make either heroes or saints.”

Miguel de Unamuno

The Tragic Sense of Life (1913), XI : The Practical Problem

“Once the needs of hunger are satisfied — and they are soon satisfied — the vanity, the necessity — for it is a necessity — arises of imposing ourselves upon and surviving in others. Man habitually sacrifices his life to his purse, but he sacrifices his purse to his vanity. He boasts even of his weakness and his misfortunes, for want of anything better to boast of, and is like a child who, in order to attract attention, struts about with a bandaged finger.”

Miguel de Unamuno

The Tragic Sense of Life (1913), III : The Hunger of Immortality

“Faith which does not doubt is dead faith.”

Miguel de Unamuno

Fe que no duda es fe muerta.
La Agonía del Cristianismo (The Agony of Christianity) (1931)

“Philosophy and religion are enemies, and because they are enemies they have need of one another. There is no religion without some philosophical basis, no philosophy without roots in religion. … the attacks which are directed against religion from a presumed scientific or philosophical point of view are merely attacks from another but opposing religious point of view.”

Miguel de Unamuno

The Tragic Sense of Life (1913), VI : In the Depths of the Abyss