doubtful point; that a thief will make his escape out of prison, if the doors of it are unguarded at midnight.

3. In matters of fact which are past or present, where neither nature, nor observation, nor custom gives us any sufficient information on either side of the question, there we may derive a probability from the attestation of wise and honest men by word or writing, or the concurring witnesses of multitudes who have seen and known what they relate, &c. This testimony in many cases will arise to the degree of moral certainty. So we believe that the plant tea grows in China; and that the Emperor of the Turks lives at Constantinople; that Julius Cæsar conquered France, and that Jesus our Saviour lived and died in Judea; that thousands were converted to the christian faith in a century after the death of Christ; and that the books which contain the christian religion, are certain histories and epistles which were written above a thousand years ago. There is an infinite variety of such propositions which can admit of no reasonable doubt, though they are not matters which are directly evident to our own senses, or our mere reasoning powers.

XXVII. When a point hath been well examined, and our own judgment settled upon just arguments, in our manly age, and after a large survey of the merits of the cause, it would be a weakness for us always to continue fluttering in suspence. We ought therefore to stand firm in such well established principles, and not be tempted to change and alter for the sake of every dif ficulty, or every occasional objection. We are not to be carried about with every flying doctrine, like children tossed to and fro, and wavering with the wind. It is a good thing to have the heart established with grace, not with meats; that is, in the great doctrines of the gospel of grace and in Jesus Christ who is the same yesterday, to-day and for ever; but it is not so necessary in the more minute matters of religion, such as meats and drinks, forms and ceremonies, which are of less importance, and for which scripture has not given such express directions. This is the advice of the great apostle; Eph. iv. 14. Heb. xiii. 8, 9.

In short, those truths which are the springs of daily practice, should be settled as soon as we can with the exercise of our best powers, after the state of manhood; but those things wherein we may possibly mistake, should never be so absolutely and finally established and determined, as though we were infallible. If the Papists of Great Britain had maintained such a resolute establishment and assurance in the days of King Henry the VIII. or Queen Elizabeth, there never had been a reformation ;nor would any Heathen have been converted even under the ministry of St. Paul, if their obstinate settlement in their idolatries had kept their eyes shut against all further light. Yet this should not hinder us from settling our most important VOL. VIII.

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principles of faith and practice, where reason shines with its clearest evidence, and the word of God plainly determines truth and duty.

XXVIII. But let us remember also, that though the gospel be an infallible revelation, we are but fallible interpreters, when we determine the sense even of some important propositions written there; and therefore though we seem to be established in the belief of any particular sense of scripture, and though there may be just calls of providence to profess and subscribe it, yet there is no need that we should resolve or promise, subscribe or swear never to change our mind; since it is possible in the nature and course of things, we may meet with such a solid and substantial objection, as may give us a quite different view of things from what we once imagined, and may lay before us sufficient evidence of the contrary. We may happen to find a fairer light cast over the same scriptures, and see reason to alter our sentiments even in some points of moment. Sic sentio, sentiam, that is, so I believe, and so I will believe, is the prison of the soul for life time, and a bar against all the improvements of the mind. To impose such a profession on other men in matters not absolutely necessary and not absolutely certain, is a criminal usurpation and tyranny over faith and conscience, and which none has power to require but an infallible dictator.

CHAP. XIX.-Of enquiring into Causes and Effects. SOME effects are found out by their causes, and some causes by their effects. Let us consider both these.

I. When we are enquiring into the causes of any particular effect or appearance, either in the world of nature, or in the civil or moral concerns of men, we may follow this method:-1. Consider what effects or appearances you have known of a kindred nature, and what have been the certain and real causes of them; for like effects have generally like causes, especially when they are found in the same sort of subjects.-2. Consider what are the several possible causes which may produce such an effect; and find out by some circumstances, how many of those possible causes are excluded in this particular case; thence proceed by degrees to the probable causes till a more close attention and inspection shall exclude some of them also, and lead you gradually to the real and certain cause.-3. Consider what things preceded such an event or appearance, which might have any influ ence upon it; and though we cannot certainly determine the cause of any thing only from its going before the effect, yet among the many forerunners, we may probably light upon the true cause, by further and more particular enquiry.. Consider whether

one cause be sufficient to produce the effect, or whether it does not require a concurrence of several causes; and then endeavour as far as possible, to adjust the degrees of influence that each cause might have in producing the effect, and the proper agency and influence of each of them therein.

So in natural philosophy, if I would find what are the principles or causes of that sensation which we call heat when I stand near the fire; here I shall find it is necessary that there be an agency of the particles of fire on my flesh, either mediately by themselves, or at least by the intermediate air; there must be a particular sort of motion and vellication imprest upon my nerves; there must be a derivation of that motion to the brain; and there must be an attention of my soul to this motion; if either of these are wanting, the sensation of heat will not be produced.

So in the moral world, if I enquire into the revolution of a state or kingdom, perhaps I find it brought about by the tyranny or folly of a prince, or by the disaffection of his own subjects; and this disaffection and opposition may arise, either upon the account of impositions in religion, or injuries relating to their civil rights; or the revolution may be effected by the invasion of a foreign army, or by the opposition of some person at home or abroad that lays claim to the government, &c. or a hero who would guard the liberties of the people; or by many of these concurring together; then we must adjust the influences of each. as wisely as we can, and not ascribe the whole event to one of them alone.

II. When we are enquiring into the effects of any particular cause or causes, we may follow this method.

1. Consider diligently the nature of every cause apart, and observe what effect every part or property of it will tend to produce.-2. Consider the causes united together in their several natures, and ways of operation; enquire how far the powers or properties of one, will hinder or promote the effects of the other, and wisely balance the proportions of the influence.-3. Consider what the subject is, in or upon which the cause is to operate; for the same cause on different subjects will oftentimes produce different effects, as the sun which softens wax will harden clay.— 4. Be frequent and diligent in making all proper experiments; in setting such causes at work whose effects you desire to know, and putting together in au orderly manner, such things as are most likely to produce some useful effects, according to the best survey you can take of all the concurring causes and circumstances.-5. Observe carefully all the events which happen either by an occasional concurrence of various causes, or by the industrious application of knowing men; and when you see any happy effect certainly produced, and often repeated, treasure it up together

with the known causes of it, amongst your improvements.-6. Take a just survey of all the circumstances which attend the operation of any cause or causes, whereby any special effect is produced, and find out as far as possible, how far any of those circumstances had a tendency either to obstruct or promote, or change those operations, and consequently how far the effect might be influenced by them.

In this manner, physicians practice and improve their skill. They consider the various known effects of particular herbs or drugs, they meditate what will be the effect of their composition, and whether the virtues of the one will exalt or diminish the force of the other, or correct any of its innocent qualities. Then they observe the native constitution, and the present temper or circumstances of the patient, and what is likely to be the effect of such a medicine on such a patient. And in all uncommon cases they make wise and cautious experiments, and nicely observe the effects of particular compound medicines on different constitutions, and in different diseases; and by these treasuries of just observations, they grow up to an honourable degree of skill in the art of healing.

So the preacher considers the doctrines and reasons, the precepts, the promises, and threatenings of the word of God, and what are the natural effects of them upon the mind; he considers what is the natural tendency of such a virtue or such a vice; he is well apprised that the representation of some of these things may convince the understanding, some may terrify the conscience, some may allure the slothful, and some encourage the desponding mind; he observes the temper of his hearers, or of any particular person that converses with him about things sacred, and he judges what will be the effects of each representation on such persons; he reviews and recollects what have been the effects of some special parts and methods of his ministry; and by a careful survey of all these, he attains greater degrees of skill in his sacred employment.

Note, In all these cases, we must distinguish those causes and effects which are naturally and necessarily connected with each other, from those which have only an accidental or contingent connection. Even in those causes where the effect is but contingent, we may sometimes arrive at a very high degree of probability; yet we cannot arrive at such certainty as where the causes operate by an evident and natural necessity, and the effects necessarily follow the operation.

See more on this subject, logic Part II. Chap. V. Sect. 7. Of the principles and rules of judging concerning things past, present and to come, by the mere use of reason.

CHAP. XX. Of the Sciences, and their use in particular Professions.

I. THE best way to learn any science, is to begin with a regular system, or a short and plain scheme of that science, well drawn up into a narrow compass, omitting the deeper and more abstruse parts of it, and that also under the conduct and instruetion of some skilful teacher. Systems are necessary to give an entire and comprehensive view of the several parts of any science, which may have a mutual influence toward the explication or proof of each other whereas if a man deals always and only in essays and discourses on particular parts of a science, he will never obtain a distinct and just idea of the whole, and may perhaps onit some important part of it after seven years reading of such occasional discourses. For this reason, young students should apply themselves to their systems much more than pamphlets. That man is never so fit to judge of particular subjects relating to any science, who has never taken a survey of the whole.

It is the remark of an ingenious writer, should a barbarous Indian, who had never seen a palace or a ship, view their separate and disjoined parts, and observe the pillars, doors, windows, cornices and turrets of the one, or the prow and stern, the ribs and masts, the ropes and shrouds, the sails and tackle of the other he would be able to form but a very lame and dark idea of either of those excellent and useful inventions. In like manner, those who contemplate only the fragments or pieces broken off from any science dispersed in short unconnected discourses, and do not discern their relation to each other, and how they may be adapted, and by their union procure the delightful symmetry of a regular scheme, can never survey an entire body of truth, but must always view it as deformed and dismembered; while their ideas, which must be ever indistinct and often repugnant, will lie in the brain unsorted, and thrown together without order or coherence: such is the knowledge of those men who live upon the scraps of the sciences.

A youth of genius and lively imagination, of an active and forward spirit, may form within himself some alluring scenes and pleasing schemes in the beginning of a science, which are utterly inconsistent with some of the necessary and substantial parts of it which appear in the middle or the end. And if he never read and pass through the whole, he takes up and is satisfied with his own hasty pleasing schemes, and treasures those errors up amongst his solid acquisitions: whereas his own labour and study farther pursued would have shewn him his early mistakes, afo cured him of his self-flattering delusions. Hence it comes of pass, that we have so many half-scholars now-a-days, and th to is so much confusion and inconsistency in the notions and opi