I have been impressed with the urgency of doing.

A bird maintains itself in the air by imperceptible balancing, when near to the mountains or lofty ocean crags; it does this by means of the curves of the winds which as they strike against these projections, being forced to preserve their first impetus bend their straight course towards the sky with divers revolutions, at the beginning of which the birds come to a stop with their wings open, receiving underneath themselves the continual buffetings of the reflex courses of the winds.

People reveal themselves completely only when they are thrown out of the customary conditions of their life.

The painter strives and competes with nature.

Medicine is the restoration of discordant elements; sickness is the discord of the elements infused into the living body.

Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind.

One painter ought never to imitate the manner of any other; because in that case he cannot be called the child of nature, but the grandchild. It is always best to have recourse to nature, which is replete with such abundance of objects, than to the productions of other masters, who learnt everything from her.