Good culture is born of a good disposition; and since the cause is more to be praised than the effect, I will rather praise a good disposition without culture, than good culture without the disposition.

Make yourself a master of perspective, then acquire perfect knowledge of the proportions of men and other animals.

In whatever system where the weight attached to the wheel should be the cause of motion of the wheel, without any doubt the center of the gravity of the weight will stop beneath the center of its axle. No instrument devised by human ingenuity, which turns with its wheel, can remedy this effect. Oh, speculators about perpetual motion, how many vain chimeras have you created in the like quest. Go and take you place with the seekers after gold.

It vexes me greatly that having to earn my living has forced me to interrupt the work and to attend to small matters.

I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.

He who does not oppose evil......commands it to be done.

Where there is most feeling, there is the greatest martyrdom.