To study the laws of history we must completely change the subject of our observation, must leave aside kings, ministers, and generals, and study the common, infinitesimally small elements by which the masses are moved.

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

It is the profession of philosophers to question platitudes that others accept without thinking twice. A dangerous profession, since philosophers are more easily discredited than platitudes, but a useful one. For when a good philosopher challenges a platitude, it usually turns out that the platitude was essentially right; but the philosopher has noticed trouble that one who did not think twice could not have met. In the end the challenge is answered and the platitude survives, more often than not. But the philosopher has done the adherents of the platitude a service: he has made them think twice.

Yo, señor, no soy malo, aunque no me faltarían motivos para serlo. Los mismos cueros tenemos todos los mortales al nacer y sin embargo, cuando vamos creciendo, el destino se complace en variarnos como si fuésemos de cera y en destinarnos por sendas diferentes al mismo fin: la muerte. Hay hombres a quienes se les ordena marchar por el camino de las flores, y hombres a quienes se les manda tirar por el camino de los cardos y de las chumberas. Aquéllos gozan de un mirar sereno y al aroma de su felicidad sonríen con la cara del inocente; estos otros sufren del sol violento de la llanura y arrugan el ceño como las alimañas por defenderse. Hay mucha diferencia entre adornarse las carnes con arrebol y colonia, y hacerlo con tatuajes que después nadie ha de borrar ya.