Not louder does the tempestuous sea bellow when the north wind strikes its foaming waves between Scylla and Charybdis; nor Stromboli nor Mount Etna when the sulphurous flames, {4} shattering and bursting open the great mountain with violence, hurl stones and earth through the air with the flame it vomits; nor when the fiery caverns of Mount Etna, spitting forth the element which it cannot restrain, hurl it back to the place whence it issued, driving furiously before it any obstacle in the way of its vehement fury ... so I, urged by my great desire and longing to see the blending of strange and various shapes made by creating nature, wandered for some time among the dark rocks, and came to the entrance of a great cave, in front of which I long stood in astonishment and ignorance of such a thing. I bent my back into an arch and rested my left hand on my knee, and with my right hand shaded my downcast eyes and contracted eyebrows. I bent down first on one side and then on the other to see whether I could perceive anything, but the thick darkness rendered this impossible; and after having remained there some time, two things arose within me, fear and desire,--fear of the dark and threatening cave, desire to see whether there were anything marvellous within. 3. I discover for man the origin of the first and perhaps of the second cause of his being. [Sidenote: Leonardo's Studies] 4. Recognizing as I do that I cannot make use of {5} subject matter which is useful and delightful, since my predecessors have exhausted the useful and necessary themes, I shall do as the man who by reason of his poverty arrives last at the fair, and cannot do otherwise than purchase what has already been seen by others and not accepted, but rejected by them as being of little value. I shall place this despised and rejected merchandise, which remains over after many have bought, on my poor pack, and I shall go and distribute it, not in the big cities, but in the poor towns, and take such reward as my goods deserve. [Sidenote: Vain Knowledge] 5. All knowledge which ends in words will die as quickly as it came to life, with the exception of the written word: which is its mechanical part. 6. Avoid studies the result of which will die together with him who studied. [Sidenote: Value of Knowledge] 7. The intellect will always profit by the acquisition of any knowledge whatsoever, for thus what is useless will be expelled from it, and what is fruitful will remain. It is impossible either to hate or to love a thing without first acquiring knowledge of it. {6} 8. Men of worth naturally desire knowledge. 9. It is ordained that to the ambitious, who derive no satisfaction from the gifts of life and the beauty of the world, life shall be a cause of suffering, and they shall possess neither the profit nor the beauty of the world. [Sidenote: On his Contemners] 10.