An artist who lacks the power of self-criticism accomplishes but little. It is good if your work stands higher than your own opinion of it; bad if it is on the same level. But it is a great disaster if your work stands lower than your judgment of it.

The vine that has grown old on an old tree falls with the ruin of that tree, and through that bad companionship must perish with it.

The painter who draws by practise and judgment of the eye without the use of reason is like the mirror which reproduces within itself all the objects which are set opposite to it without knowledge of the same.

True and great love springs out of great knowledge, and where you know little you can love but little or not at all.

The deeper the feeling, the greater the pain

To such an extent does nature delight and abound in variety that among her trees there is not one plant to be found which is exactly like another; and not only among the plants, but among the boughs, the leaves and the fruits, you will not find one which is exactly similar to another.

Those who become enamoured of the art, without having previously applied to the diligent study of the scientific part of it, may be compared to mariners who put to the sea in a ship without rudder or compass and therefore cannot be certain of arriving at the wished for port.