Necessity is the mistress and guardian of Nature. - Leonardo da Vinci

Simplicity is the ultimate sophistication.
When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.
Learning never exhausts the mind.
Art is never finished, only abandoned.
Painting is poetry that is seen rather than felt, and poetry is painting that is felt rather than seen.
The human foot is a masterpiece of engineering and a work of art.
It had long since come to my attention that people of accomplishment rarely sat back and let things happen to them. They went out and happened to things.
I have been impressed with the urgency of doing. Knowing is not enough; we must apply. Being willing is not enough; we must do.
As a well-spent day brings happy sleep, so a life well spent brings happy death.
Water is the driving force of all nature.

The body which is nearest to the light casts the largest shadow, and why? If an object placed in front of a single light is very close to it you will see that it casts a very large shadow on the opposite wall, and the farther you remove the object from the light the smaller will the image of the shadow become.

I ask how far away the eye can discern a non-luminous body, as, for instance, a mountain. It will be very plainly visible if the sun is behind it; and could be seen at a greater or less distance according to the sun's place in the sky.