And thou, O man, who wilt gaze in this work of mine on the marvellous works of nature, if thou thinkest it would be an act of wickedness to destroy it, think how much more wicked it is to take the life of a man; and if this his structure appears to thee a miraculous work of art, remember that it is nothing in comparison with the soul which inhabits this structure; for verily, whatever it may be, it is divine. Let it, then, dwell in His work and at His good will, and let not thy rage or malice destroy so great a thing as life, for he who does not value it does not deserve it.
The Experimental Method
79.
By these rules thou wilt be able to distinguish falsehood from truth by means of which knowledge men aim at possible things with greater moderation; and do not veil thyself in ignorance, for the result of this would be that thou wouldst be ineffectual and fall into melancholy and despair.
Of Navigation below the Waters
80.
How by the aid of a machine many may remain for some time under water. And how and why I do not describe my method of remaining under water and of living long without food; and I do not publish nor divulge these things by reason of the evil nature of man, who would use them for assassinations at the bottom of the sea and to destroy and sink ships, together with the men on board of them; and notwithstanding I will teach other things which are not dangerous....
Of Physiognomy
81.
I will not dwell on false physiognomy and chiromancy because there is no truth in them, and this is manifest because chimeras of this kind have no scientific foundation. It is true that the lineaments of the face partly reveal the character of men, their vices and temperaments; but in the face: (a) the features which separate the cheeks from the lips, and the nostrils and cavities of the eyes, are strongly marked if they belong to cheerful and good-humoured men, and if they are slightly marked it denotes that the men to whom they belong are given to meditation, (b) Those whose features stand out in great relief and depth are brutal and bad-tempered, and reason little, (c) Those who have strongly marked lines between the eyebrows are bad-tempered, (d) Those who have strongly marked lines on the forehead are men full of concealed or unconcealed bewailing.