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… 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.