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.

Animals will be seen on the earth who will always be fighting against each other with the greatest loss and frequent deaths on each side. And there will be no end to their malignity; by their strong limbs we shall see a great portion of the trees of the vast forests laid low throughout the universe; and, when they are filled with food the satisfaction of their desires will be to deal death and grief and labour and wars and fury to every living thing; and from their immoderate pride they will desire to rise towards heaven, but the too great weight of their limbs will keep them down. Nothing will remain on earth, or under the earth or in the waters which will not be persecuted, disturbed and spoiled, and those of one country removed into another. And their bodies will become the sepulture and means of transit of all they have killed.

O Earth! why dost thou not open and engulf them in the fissures of thy vast abyss and caverns, and no longer display in the sight of heaven such a cruel and horrible monster?

The smallest natural point is larger than all mathematical points, and this is proved because the natural point has continuity, and any thing that is continuous is infinitely divisible; but the mathematical point is indivisible because it has no size.