AN _Italian_ Philosopher destroyed this whole Doctrine at once, by a simple and easy Experiment. He exposed a Piece of raw Flesh in a glass Vessel well covered with Gauze to the Air and Sun, and found that it putrefied without producing any living Creatures. This shews how careful we ought to be with Respect to Facts; for till this Experiment was made, no Body doubted that Vermin were bred by, as well as in putrefied Bodies; whereas we are now satisfied that the Heat of the Sun can no more produce a Worm or a Maggot, than a Horse or an Elephant. By the same Examination we might open the Way to Knowledge, by driving out a Multitude of other Errors. But the Humour of taking Things for granted without inquiring into them, and then endeavouring to account for them by dint of Reasoning, amuses us with a false shew of Wisdom, and encourages us to persist obstinately in the Maintenance of weak and foolish Notions. TO apply this to the Subject of which we are treating. It is certainly a curious and a useful Thing to understand the Nature of the Weather, and to know how the Changes that happen in it come to pass. The Business is to find out the true Way of coming at this kind of Knowledge, and upon the Principles that I have advanced, it is very evident that the, only certain Way of coming at it is by Observation. This is a slow but a sure Method of arriving at Truth, and the Specimen here given us, of _one_ Man's Observations, is enough to convince us that a little Diligence and Application would soon go a great Way towards forming a Body of such Observations as might enable us to understand the Weather thoroughly, and to predict its Changes and Alterations with a great Degree of Certainty. If we will not take this Pains, we must content ourselves with what hath been already discovered, or if our Conditions of Life exclude us from the Opportunities of making such Observations, it is certainly a right Thing to help ourselves by inquiring into, and reasoning upon such Observations as other People have made and to facilitate this as far as possible, I have taken the Pains to write this Commentary upon our Shepherd's Rules; which I hope will render them more useful, or at least secure them that Regard which they deserve.