Threats alone, are the weapons of the threatened man.

If you are representing a white body let it be surrounded by ample space, because as white has no colour of its own, it is tinged and altered in some degree by the colour of the objects surrounding it

Art lives from constraints and dies from freedom.

Of several bodies, all equally large and equally distant, that which is most brightly illuminated will appear to the eye nearest and largest.

There are many kinds of beauty as people who possess 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.

Those who condemn the supreme certainty of mathematics feed on confusion, and can never silence the contradictions of the sophistical sciences which lead to eternal quackery.