'We can comprehend what is meant by contaminating a man's habits or disposition, or even imagination. But there is no analogy on these points in reference to the understanding. There is contamination, there is evil, in preposterous and obscene images crowding before the intellectual vision, notwithstanding a full and distinct perception of their character--but there is no contamination, no evil, in a thousand false arguments coming before the understanding, if their quality is clearly discerned. The only possible evil in this case is mistaking false for true--but the man who shrinks from investigation lest he should mistake false for true, can have no reason for supposing himself free from that delusion in his actual opinions. Besides these objections to inquiry, there are other prejudices of a similar character, forming serious impediments to the attainment of truth. 'One of these is a _fear that we may search too far, and become chargeable with presumption in prying into things we ought not to know_. A few words will suffice to prove that nothing can be more irrational and absurd. We have already shown that true opinions are conducive to the welfare of mankind--and the prosecution of inquiry is therefore a process from which we have everything to hope and nothing to fear, and to which there are no limits but such as the nature of our own faculties pre scribes. 'A second prejudice--that _we may contract guilt, if, in the course of our researches, we miss the right conclusion, and had therefore better let inquiry alone_--is still more influential in preventing those investigations which it is our duty to make. As our opinions on any subject are not voluntary acts, but involuntary effects, in whatever conclusions our researches terminate they can involve us in no culpability. All that we have to take care of is, to bestow on every subject an adequate and impartial attention. Having done this, we have discharged our duty; and it would be irrational and unmanly to entertain any apprehension for the result.