As soon as any one belongs to a narrow creed in science, every unprejudiced and true perception is gone.

Fortunately, we can take in only so much misfortune; what exceeds that limit either destroys us or leaves us indifferent.

I have, alas! Philosophy, Medicine, Jurisprudence too, And to my cost Theology, With ardent labor, studied through. And here I stand, with all my lore, Poor fool, no wiser than before.

And I have again observed, my dear friend, in this trifling affair, that misunderstandings and neglect occasion more mischief in the world than even malice and wickedness. At all events, the two latter are of less frequent occurrence.

There are people who pay attention to the weaknesses of their friends; that is to no avail. I have always closely watched and profited from the strengths of my adversaries.

With knowledge comes more doubt.

All truths are old, and all that we have to do is recognize and utter them anew.