_Direct._ VIII. Be sure in all your progress that you keep a distinct knowledge of things certain and things uncertain, searchable and unsearchable, revealed and unrevealed; and lay the first as your foundation, yea, rather keep the knowledge of them as your science of physics by itself, and let no obscurity in the rest cause you to question certain things; nor ever be so perverse as to try things known, by things unknown, and to argue _a minus notis_. Lay no stress on small or doubtful things.
_Direct._ IX. Metaphysics as now taken is a mixture of organical and real knowledge; and part of it belongeth to logic, (the organical part,) and the rest is theology, pneumatology, and the highest parts of ontology, or real science.
_Direct._ X. In studying philosophy, 1. See that you neither neglect any helps of those that have gone before you, under pretence of taking nothing upon trust, and of studying the naked things themselves (for if every man must begin all anew, as if he had been the first philosopher, knowledge will make but small proficiency). 2. Nor yet stick in the bare belief of any author whatsoever, but study all things in their naked natures and proper evidences, though by the helps that are afforded you by others. For it is not science, but human belief, else, whoever you take it from.
_Direct._ XI. So certain are the numerous errors of philosophers, so uncertain a multitude of their assertions, so various their sects, and so easy it is for any to pull down much which the rest have built, and so hard to set up any comely structure that others in like manner may not cast down; that I cannot persuade you to fall in with any one sort or sect, who yet have published their sentiments to the world. The Platonists made very noble attempts in their inquiries after spiritual being; but they run into many unproved fanaticisms, and into divers errors, and want the desirable helps of true method. The wit of Aristotle was wonderful for subtilty and solidity; his knowledge vast; his method (oft) accurate; but many precarious, yea erroneous conceptions and assertions, are so placed by him, as to have a troubling and corrupting influence into all the rest. The Epicureans or Democratists were still and justly the contempt of all the sober sects; and our late Somatists that follow them, yea, and Gassendus, and many that call themselves Cartesians, yea, Cartesius himself, much more Berigardus, Regius, and Hobbes, do give so much more to mere matter and motion, than is truly due, and know or say so much too little of spirits, active natures, vital powers, which are the true principles of motion, that they differ as much from true philosophers, as a carcass or a clock from a living man. The stoics had noble ethical principles, and they (and the Platonists with the cynics) were of the best lives; but their writings are most lost, and little of their physics fully known to us, and that also hath its errors. Patricius is but a Platonist so taken with the nature of light, as insisting on that in fanatical terms, to leave out a great deal more that must he conjoined. Telesius doth the like by heat and cold, heaven and earth, and among many observable things, hath much that is unsound and of ill consequence. Campanella hath improved him, and hath many hints of better principles (especially in his primalities) than all the rest; but he fanatically runs them up into so many unproved and vain, yea, and mistaken superstructures, as that no true body of physics can be gathered out of all his works. The attempt that pious Commenius hath made in his small manual hath much that is of worth; but far short of accurateness. The Hermetical philosophers have no true method of philosophy among them; and to make their three or five principles to be so many elements, or simple bodies, constituting all compounds, and form up a system of philosophy on their suppositions, will be but a trifle, and not to satisfy judicious minds; especially considering how defective their philosophy is made by their omissions. Lullius and his followers fit not their method to the true order of the matter. Scaliger, Scheggius, Wendeline, and Sennertus (especially in his Hypomnemata) were great men, and have many excellent things; but too much of Aristotle's goeth for current with them. My worthy, learned, and truly pious friend Mr. Sam. Gott, in his new book on Gen. i. hath many excellent notions, and much that is scarce elsewhere to be met with; but the tedious paragraphs, the defect of method, and several unproveable particulars, make it, like all human works, imperfect.