554 NOVUM ORGANUM. [BOOK II 



of gravity, which relates to the intercourse of dense bodies only 

 Again, tlie desire of a private good does not in general prevail 

 against that of a public one, except where the quantities are 

 small. Would that such were the case in civil matters ! 



XLIX. In the twenty-fifth rank of prerogative instances we 

 will place suggesting instances ; such as suggest, or point out, 

 that which is advantageous to mankind; for bare power and 

 knowledge in themselves exalt rather than enrich human nature. 

 We must, therefore, select from the general store, such things as 

 are most useful to mankind. We shall have a better opportunity 

 ot discussing these when we treat of the application to practice . 

 besides, in the work of interpretation, we leave room, on every 

 subject, for the human or optative chart ; for it is a part of 

 science to make judicious inquiries and wishes. 



L. In the twenty-sixth rank of prerogative instances we will 

 place the generally useful instances. They are such as relate to 

 various points, and frequently occur, sparing by that means con 

 siderable labour and new trials. The proper place for treating 

 of instruments and contrivances, will be that in which we speak 

 of the application to practice, and the methods of experiment. 

 All that lias hitherto been ascertained, and made use of, will be 

 described in the particular history of each art. At present, we 

 will subjoin a few general examples of the instances in question. 



Man acts, then, upon natural bodies (besides merely bringing 

 them together or removing them) by seven principal methods : 

 1. By the exclusion of all that impedes and disturbs ; 2. by 

 compression, extension, agitation, and the like ; 3. by heat and 

 cold; 4. by detention in a suitable place; 5. by checking or 

 directing motion ; 6. by peculiar harmonies ; 7. by a seasonable 

 and proper alternation, series, and succession of all these, or, at 

 least, of some of them. 



1. With regard to the first, common air, which is always at 

 hand, and forces its admission, as also the rays of the heavenly 

 bodies, create much distv. dance. Whatever, therefore, tends to 

 exclude them may well be considered as generally useful. The 

 substance and thickness of vessels in which bodies are placed 

 when prepared for operations may be referred to this head. So 

 also may the accurate methods of closing vessels by consolida 

 tion, or the lutum sapientia, as the chemists call it. The exclu 

 sion of air by means of liquids at the extremity is also very use 

 ful, as when they pour oil on wine, or the juices of herbs, which 

 by spreading itself upon the top like a cover, preserves them 

 uninjured from the air. Powders, also, are serviceable, for 

 although they contain air mixed up in them, yet they ward off 

 the power of the mass of circumambient air, which is seen in the 

 preservation of grapes and other fruits in sand or flour. Wax, 

 Loney, pitch, and other resinous bodies, are well used in ordef 



