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.

Therefore if I must direct you according to my judgment, I must advise you, 1. To suppose that philosophers are all still in very great darkness, and there is much confusion, defectiveness, error, and division, and uncertainty among them. 2. Therefore addict not yourselves absolutely to any sect of them. 3. Let your first studies of them all leave room for the changing of your judgment, and do not too hastily fix on any of their sentiments as sure, till you have heard what others say, and with ripened understandings have deeply and long studied the things themselves. 4. Choose out so much of the certainties and useful parts of physics as you can reach to, and make them know their places in subserviency to your holy principles and ends; and rather be well content with so much, than to lose too much time in a vain fatiguing of your brains for more.

I have made some attempt to draw out so much, especially de mundo et de homine, in my "Methodus Theologiæ," though I expect it should no more satisfy others, than any of theirs have satisfied me.

Direct. XII. When you have well stated your ontology or real science, then review your logic and organical part of metaphysics; and see that verba rebus aptentur; fetch then your words and organical notions from the nature of the things. Abundance are confounded by taking up logical notions first which are unsuitable to true physical beings.

Direct. XIII. Somewhat of ethics may be well learned of philosophers, but it is nothing to the Scripture's christian ethics.

Direct. XIV. Somewhat of artificial rhetoric and oratory should be known; but the oratory which is most natural, from the evidence of things, well managed by a good understanding and elocution, which hath least of appearing art or affectation, is ever the most effectual, and of best esteem.

Direct. XV. The doctrine of politics, especially of the nature of government and laws in general, is of great use to all that will ever understand the nature of God's government and laws, that is, of religion. Though there be no necessity of knowing the government and laws of the land or of other countries, any further than is necessary to our obedience or outward concernments, yet so much of government and laws as nature and Scripture make common to all particular forms and countries, must be known by him that will understand morality or divinity, or will ever study the laws of the land. And it is a preposterous course, and the way of ignorance and error, for a divine to study God's laws, and a lawyer man's laws, before either of them know in general what a law or what government is, as nature notifieth it to us.