The painter will produce pictures of little merit if he takes the works of others as his standard.

I am not poor. Poor are those who desire many things.

I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.

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

Marriage is like putting your hand into a bag of snakes in the hope of pulling out an eel.

To speak of this subject you must... explain the nature of the resistance of the air, in the second the anatomy of the bird and its wings, in the third the method of working the wings in their various movements, in the fourth the power of the wings and the tail when the wings are not being moved and when the wind is favourable to serve as guide in various movements.

When that which loves is united to the thing beloved it can rest there; when the burden is laid down it finds rest there. There will be eternal fame also for the inhabitants of that town, constructed and enlarged by him.