This work should commence with the conception of man, and should describe the nature of the womb, and how the child inhabits it, and in what stage it dwells there, and the manner of its quickening and feeding, and its growth, and what interval there is between one stage of growth and another, and what thing drives it forth from the body of the mother, and for what reason it sometimes emerges from the belly of its mother before the due time.
Leonardo da VinciFor 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.
Leonardo da VinciIt's not enough that you believe what you see. You must also understand what you see.
Leonardo da VinciIf you are alone you belong entirely to yourself. If you are accompanied by even one companion you belong only half to yourself or even less in proportion to the thoughtlessness of his conduct and if you have more than one companion you will fall more deeply into the same plight.
Leonardo da Vinci