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.
The interest which the corrupt part of mankind have in hardening themselves against every motive to amendment, has disposed them to give to these contradictions, when they can be produced against the cause of virtue, that weight which they will not allow them in any other case. They see men act in opposition to their interest, without supposing that they do not know it; those who give way to the sudden violence of passion, and forsake the most important pursuits for petty pleasures, are not supposed to have changed their opinions, or to approve their own conduct In moral or religious questions alone, they determine the sentiments by the actions, and charge every man with endeavouring to impose upon the world, whose writings are not confirmed by his life. They never consider that themselves neglect or practise something every day inconsistently with their own settled judgment, nor discover that the conduct of the advocates for virtue can little increase or lessen the obligations of their dictates ; argument is to be invalidated only by argument, and is in itself of the same force, whether or not it convinces him by whom it is proposed.
Yet since this prejudice, however unreasonable, is always likely to have some prevalence, it is the duty of every man to take care lest he should hinder the efficacy of his own instructions. When he desires to gain the belief of others, he should show that he believes himself; and when he teaches the fitness of virtue by his reasonings, he should, by his example, prove its possibility. Thus much at least maybe required of him, that he shall not act worse than others, because he writes better; nor imagine that, by the merit of his genius, he may claim indulgence, beyond mortals of the lower classes, and be excused for want of prudence, or neglect of virtue.
Samuel Johnson The Works of Samuel Johnson. p.34