He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may cast.

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

For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.

Perspective is nothing more than a rational demonstration applied to the consideration of how objects in front of the eye transmit their image to it, by means of a pyramid of lines. The Pyramid is the name I apply to the lines which, starting from the surface and edges of each object, converge from a distance and meet in a single point.

Let not your rage or malice destroy a life.

There are many occasions when the muscles that form the lips of the mouth move the lateral muscles that are joined to them, and there are an equal number of occasions when these lateral muscles move the lips of this mouth, replacing it where it cannot return of itself, because the function of muscle is to pull and not to push except in the case of the genitals and the tongue.

There shall be wings! If the accomplishment be not for me, 'tis for some other. The spirit cannot die; and man, who shall know all and shall have wings.