Quantum cryptography doesn't rely on the difficulty of mathematical problems, but on the fundamental laws of physics.

La poesía es la única prueba concreta de la existencia del hombre.

The melancholy science from which I make this offering to my friend relates to a region that from time immemorial was regarded as the true field of philosophy, but which, since the latter's conversion into method, has lapsed into intellectual neglect, sententious whimsy, and finally oblivion.

现代教育者的任务不是砍伐丛林，而是灌溉沙漠。