LXXXVII. It is much to be lamented, that those who are called professors in the schools, do not know more of the nature of things than the vulgar. But what would you think, if I was to say now, they know even less? It would seem, as if I was advancing an extravagant paradox; but notwithstanding this, I assert that the proposition is a most true one, and may be easily proved; for as experience is the only channel, through which a knowledge of nature can be conveyed; they must have the best experimental knowledge of natural things, who in various mechanical occupations, work up various natural entities; and not those who amuse themselves with speculations, and live retired in schools. A fisherman, knows something of the properties of fish; a pilot, of the winds and the tides; a sportsman, of birds and wild animals; and a husbandman, of the generation and increase of plants. But what does the philosopher know? why, he knows how to raise doubts about every thing, and that is all. Thus the school of physics is a theatre, where people are taught to doubt without end. I say without end, because it is scarce possible the period should ever arrive, when they will be able to pass from doubt to certainty. This may be clearly inferred, by their disputing at this day with the same obstinacy, the same questions they disputed two hundred years ago. If any elucidation, or certain knowledge, has been acquired with respect to here and there a physical theorem, we are not indebted for it to the schools, but owe it to the benefit of experience, which comes from the world at large. We may thank the experiments of Torriceli, Monsieur Pascal, Otho Guerricus, and Boyle, for our knowledge that the air is ponderous. If we are certain, that the blood circulates from the heart through the arteries, and is returned by the veins, we owe the discovery to the anatomical observations of Peter Paul Sarpi and William Harvey. If we are clear, that the chyle is not conveyed to the liver, but to the heart; what ascertained this truth, but the diligent and practical scrutinies of John Paqueto, Thomas Bartolino, and the Englishman Lowther? Experience has been the only arbitrator, which has settled some disputes, and banished certain errors from the schools; and wherever matters have been left to speculation and reasoning, the suit still remains depending and undetermined. One age and another passes away, and the world during the whole time, has been accustomed to hear the same vociferations, the same arguments, and the same distinctions; and has seen the obstinacy of the contending parties, transferred, as if it were by hereditary succession, from professor to professor, without the least prospect, either of victory or reconciliation. SECT. XXIV.