5. He that will walk uprightly, must have both a solid and a large understanding, to know things truly as they are, and to see all particulars which must be taken notice of, in all the cases which he must determine, and all the actions which his integrity is concerned in. 1. There is no walking uprightly in the dark. Zeal will cause you to go apace; but not at all to go right, if judgment guide it not. Erroneous zeal will make you to do evil with double violence, and with blasphemous fathering your sins on God, and with impenitence and justification of your sin.[5] This made Paul mad in persecuting the church. Prov. xv. 21, "Folly is joy to him that is destitute of wisdom; but a man of understanding walketh uprightly." No man can do that well which he understandeth not well. Therefore you must study and take unwearied pains for knowledge; wisdom never grew up with idleness, though the conceit of wisdom doth no where more prosper. This age hath told us to what dangerous precipices men will be carried by an ignorant zeal. 2. And the understanding must be large, or it cannot be solid; when many particulars are concerned in an action, the overlooking of some may spoil the work. Narrow-minded men are turned as the weathercock, with the wind of the times, or of every temptation; and they seldom avoid one sin, but by falling into another. It is prudence that must manage an upright life: and prudence seeth all that must be seen, and putteth every circumstance into the balance; for want of which, much mischief may be done, while you seem to be doing the greatest good.[6] "The prudent man looketh well to his going," Prov. xiv. 15. "See therefore that ye walk circumspectly, (at a hair's breadth,) not as fools, but as wise." 6. But because you will object, that, alas, few even of the upright, have wits so strong as to be fit for this, I add, that he that will walk uprightly, must in the great essential parts of religion have this foresaid knowledge of his own, and in the rest at least he must have the conduct of the wise. And therefore, 1. He must be wise in the great matters of his salvation, though he be weak in other things. 2. And he must labour to be truly acquainted who are indeed wise men, that are meet to be his guides: and he must have recourse to such in cases of conscience, as a sick man to his physician. It is a great mercy to be so far wise, as to know a wise man from a fool, and a counsellor from a deceiver.[7]