How the understanding is best conducted to the knowledge of science, by what steps it is to be led forwards in its pursuit, how it is to be cured of its defects, and habituated to new studies, has been the inquiry of many acute and learned men, whose observations I shall not either adopt or censure: my purpose being to consider the moral discipline of the mind, and to promote the increase of virtue rather than of learning. This inquiry seems to have been neglected for want of remembering, that all action has its origin in the mind, and that therefore to suffer the thoughts to be vitiated, is to poison the fountains of morality; irregular desires will produce licentious practices; what men allow themselves to wish they will soon believe, and will be at last incited to execute what they please themselves with contriving. For this reason the casuists of the Roman church, who gain, by confession, great opportunities of knowing human nature, have generally determined that what it is a crime to do, it is a crime to think[35]. Since by revolving with pleasure the facility, safety, or advantage of a wicked deed, a man soon begins to find his constancy relax, and his detestation soften; the happiness of success glittering before him, withdraws his attention from the atrociousness of the guilt, and acts are at last confidently perpetrated, of which the first conception only crept into the mind, disguised in pleasing complications, and permitted rather than invited. No man has ever been drawn to crimes by love or jealousy, envy or hatred, but he can tell how easily he might at first have repelled the temptation, how readily his mind would have obeyed a call to any other object, and how weak his passion has been after some casual avocation, till he has recalled it again to his heart, and revived the viper by too warm a fondness. Such, therefore, is the importance of keeping reason a constant guard over imagination, that we have otherwise no security for our own virtue, but may corrupt our hearts in the most recluse solitude, with more pernicious and tyrannical appetites and wishes than the commerce of the world will generally produce; for we are easily shocked by crimes which appear at once in their full magnitude; but the gradual growth of our own wickedness, endeared by interest, and palliated by all the artifices of self-deceit, gives us time to form distinctions in our own favour, and reason by degrees submits to absurdity, as the eye is in time accommodated to darkness. In this disease of the soul, it is of the utmost importance to apply remedies at the beginning; and therefore I shall endeavour to shew what thoughts are to be rejected or improved, as they regard the past, present, or future; in hopes that some may be awakened to caution and vigilance, who, perhaps, indulge themselves in dangerous dreams, so much the more dangerous, because, being yet only dreams, they are concluded innocent.