41. Præmittendum 3º, nondum rerum naturalium, quæ sunt in mundo, satis perspectam esse existentiam, aut naturam, ut proinde aliquid negandum sit ex eo, quod de illo nunquam alias dictum, aut scriptum fuerit. Patet enim tractu temporis detectas esse novas terras, quas Antiqui nostri ignorarunt, novaque animalia, herbas, plantas, fructus, semina nunquam alias visa; et si pervia esset Terra Australis incognita, cujus indagatio, et lustratio a multis hucusque incassum tentata est, adhuc nova nobis alia panderentur. Patet adhuc, quod per inventionem microscopii, et alias machinas, et organa Philosophiæ experimentalis modernæ, sicut etiam per exactiorem indaginem Anatomistarum, multarum rerum naturalium existentiam, vires, naturamque tum innotuisse, tum dietim innotescere, quæ præcedentes Philosophi ignorarunt, ut patet in auro fulminante, phosphoro, et centum aliis chymicis experimentis, circulatione sanguinis, venis lacteis, vasis lymphaticis, et aliis hujusmodi quæ nuper Anatomistæ adinvenerunt. Proinde ineptum erit aliquod exsibillare ex hoc quod de eo nullus Antiquorum scripserit, attento maxime Logicorum axiomate, quod locus ab auctoritate negativa non tenet. 41. Thirdly, I premise that neither the existence nor the nature of the natural things in this world has been sufficiently investigated to allow of denying a fact, merely because it has never been previously spoken of or written about. In the course of time have not new lands been discovered which the Ancients knew not of? New animals, herbs, plants, fruits and seeds, never seen elsewhere? And if that mysterious Austral land came at last to be explored, as has been to this day vainly tried by so many travellers, what unforeseen disclosures would be the result! Through the invention of the microscope and other instruments used by modern experimental Philosophy, combined with the more exact methods of investigation of Anatomists, have there not been, and are there not, every day, brought to light the existence, qualities and characteristics of a number of natural things unknown to ancient Philosophers, such as fulminating gold, phosphorus, and a hundred other chemical compounds, the circulation of the blood, the lacteal vessels, the lymph-ducts and other recent anatomical discoveries? To deride a doctrine because it does not happen to be mentioned in any ancient author would therefore be absurd, especially bearing in mind this axiom of Logic: _locus ab auctoritate negativa non tenet_.