O speculators about perpetual motion, how many vain chimeras have you created in the like quest? Go and take your place with the seekers after gold.

All our knowledge is the offspring of our perceptions.

The light and heat of the universe comes from the sun, and its cold and darkness from the withdrawal of the sun.

... we might say that the earth has a spirit of growth; that its flesh is the soil, its bones the arrangement and connection of the rocks of which the mountains are composed, its cartilage the tufa, and its blood the springs of water.

Our life is made by the death of others.

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.

Some promises and time disappoint us