hinder us from settling our most important 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, sic sentiam, i. e. 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 inquiring 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 inquiring 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 influence 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 inquiry.

4. 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 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 impressed 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 inquire 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 inquiring 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: inquire how far the powers or properties of one will hinder or promote the effects of the other, and wisely balance the propositions of their 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 an 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 applications of knowing men and wheh 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 practise and improve their skill. They consider the various known effects of particular herbs or drugs, they meditate what will be the effects of their composition, and whether the virtues of the one will exalt or diminish the force of the other, or correct any of its nocent 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 ob serve the effects of particular compound medicines on different constitutions and in different diseases, and by these treasures 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 apprized 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 con

verses 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.

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 instruction 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