(4.) Fourthly, There are also _accidental inclinations_, which, though not customary, have the force of a second nature, because their working is violent and impetuous, and these, which are from a wounded conscience or excesses of melancholy, have a bias more than ordinary; they lay violent hands upon the understanding, and with a mighty torrent run it down. So that if an error be offered that is suitable to such fears or misapprehensions, it can scarce miss of success. The extraordinary turbulences of some other passions, as anger, love, &c., have the like effect. (5.) Fifthly, _Vicious habits_ do so much bias the mind, that the understanding must needs be defiled by them. Nothing can more prepare the mind to a wicked error than a wicked life. An error of indulgence being so grateful to corruption may readily find favour with the understandings of those that know not to do good, because they have accustomed themselves to do evil. (6.) Sixthly, There are _external things_ that have no less power on the understanding than any of the foregoing; and these are custom, education, and interest. These stick so close, and work so subtly, that though there are few that are not, in disputable cases, influenced by them, yet none are able or willing to take notice how and by what steps they do engage them to pass sentence against truth. And indeed that man must have a singular measure of suspicious watchfulness and clear integrity that is not deceived by them. And the best way to keep clear of the mischief that these may do us, is to be severe in our suspicions on that side to which custom and interest have their tendencies. (7.) Seventhly, I might note that there is something considerable to this purpose _in the nature of spirits_. Some spirits are unfixed and volatile, and these are soon altered by their own unsteadiness. Others are tenacious and unflexible; and if such be first set wrong, it is not an easy thing that will reduce them to truth. Others are soft and ductile, persuaded by good words as soon as strong arguments. And again, some are of such a rough, sour, contradictious temper, that they will sooner choose to run wrong than comply with the persuasions of those that offer truth, even for that reason, because they are persuaded to it; so that the truth which, if none had minded them, they of themselves would have embraced, they will now refuse when it is pressed upon them, out of a cross and thwarting humour, because they hate nothing more than to do as they are bidden.