I always carry the Ethics of Spinoza with me. [Original in German: Ich führe, die Ethik von Spinoza immer bei mir; er hat die Mathematik in die Ethik… - Benedictus de Spinoza

How would it be possible, if salvation were ready to our hand, and could without great labor be found, that it should be by almost all men neglected? But all things excellent are as difficult as they are rare.

Twenty-some years ago, when at the age of forty I returned to the study of the Ethics, which had been 'my book' during adolescence, the theoretical climate in which I found myself immersed had changed to such an extent that it was difficult to tell if the Spinoza standing before me then was the same one who had accompanied me in my earliest studies.

يظن الناس أنفسهم أحرارًا لأنهم شاعرون بإرادتهم ورغباتهم، ولكنهم يجهلون الأسباب التي أفضت بهم إلى الإرادة والرغبة