The mathematicians are well acquainted with the difference between pure science, which has to do only with ideas, and the application of its laws to the use of life, in which they are constrained to submit to the imperfection of matter and the influence of accidents. Thus, in moral discussions, it is to be remembered that many impediments obstruct our practice, which very easily give way to theory. The speculatist is only in danger of erroneous reasoning; but the man involved in life, has his own passions, and those of others, to encounter, and is embarrassed with a thousand inconveniencies, which confound him with variety of impulse, and either perplex or obstruct his way. He is forced to act without deliberation, and obliged to choose before he can examine: he is surprised by sudden alterations of the state of things, and changes his measures according to superficial appearances; he is led by others, either because he is indolent, or because he is timorous; he is sometimes afraid to know what is right, and sometimes finds friends or enemies diligent to deceive him. We are, therefore, not to wonder that most fail, amidst tumult, and snares, and danger, in the observance of those precepts, which they lay down in solitude, safety, and tranquillity, with a mind unbiassed, and with liberty unobstructed. It is the condition of our present state to see more than we can attain; the exactest vigilance and caution can never maintain a single day of unmingled innocence, much less can the utmost efforts of incorporated mind reach the summit of speculative virtue. It is, however, necessary for the idea of perfection to be proposed, that we may have some object to which our endeavours are to be directed; and he that is most deficient in the duties of life, makes some atonement for his faults, if he warns others against his own failings, and hinders, by the salubrity of his admonitions, the contagion of his example. Nothing is more unjust, however common, than to charge with hypocrisy him that expresses zeal for those virtues which he neglects to practise; since he may be sincerely convinced of the advantages of conquering his passions, without having yet obtained the victory, as a man may be confident of the advantages of a voyage, or a journey, without having courage or industry to undertake it, and may honestly recommend to others, those attempts which he neglects himself.