Anyone who in discussion relies upon authority uses, not his understanding, but rather his memory.
The function of muscle is to pull and not to push, except in the case of the genitals and the tongue.
Common Sense is that which judges the things given to it by other senses.
While I thought that I was learning how to live, I have been learning how to die.
As a well-spent day brings happy sleep, so a life well spent brings happy death.
I have offended God and mankind because my work didn't reach the quality it should have.
Experience does not err. Only your judgments err by expecting from her what is not in her power.
Just as courage imperils life; fear protects it.
Men of lofty genius when they are doing the least work are most active.
[Three classes of people]: Those who see. Those who see when they are shown. Those who do not see.
Just as iron rusts from disuse, even so does inaction spoil the intellect.
Our life is made by the death of others.
Iron rusts from disuse, stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigors of the mind.
As every divided kingdom falls, so every mind divided between many studies confounds and saps itself.
A good painter is to paint two main things, men and the working of man's mind.
Patience serves as a protection against wrongs as clothes do against cold. For if you put on more clothes as the cold increases, it will have no power to hurt you. So in like manner you must grow in patience when you meet with great wrongs, and they will be powerless to vex your mind.
Every now and then go away, have a little relaxation, for when you come back to your work your judgment will be surer. Go some distance away because then the work appears smaller and more of it can be taken in at a glance and a lack of harmony and proportion is more readily seen.
I roamed the countryside searching for answers to things I did not understand. Why thunder lasts longer than that which causes it, and why immediately on its creation the lightning becomes visible to the eye while thunder requires time to travel. How the various circles of water form around the spot which has been struck by a stone and why a bird sustains itself in the air. These questions and other strange phenomena engaged my thought throughout my life.
Time stays long enough for those who use it.
Nothing can be love or hated unless it is first known.
The noblest pleasure is the joy of understanding.