All the elements will be seen mixed together in a great whirling mass, now borne towards the centre of the world, now towards the sky; and now furiou… - Leonardo da Vinci

When you wish to see whether the general effect of your picture corresponds with that of the object represented after nature, take a mirror and set it so that it reflects the actual thing, and then compare the reflection with your picture, and consider carefully whether the subject of the two images is in conformity with both, studying especially the mirror. The mirror ought to be taken as a guide... you see the picture made upon one plane showing things which appear in relief, and the mirror upon one plane does the same. The picture is on one single surface, and the mirror is the same. ...if you but know well how to compose your picture it will also seem a natural thing seen in a great mirror.

Men standing in opposite hemispheres will converse and deride each other and embrace each other, and understand each other's language.

Ask counsel of him who rules himself well.