"It appears, then, that the rule for attaining ... clearness of apprehension is as follows: _Consider what effects, which might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object"._ (Italics mine). An application of this method to a conception which particularly concerns logic occupies the last section of the article,--a use of the method to make clear our conception of "reality". Considering clearness in the sense of familiarity, no idea could be clearer than this, for everyone uses it with perfect confidence. Clearness in the sense of definition is only slightly more difficult,--"we may define the real as that whose characters are independent of what anybody may think them to be". But however satisfactory this is as a definition, it does not by any means make our idea of reality perfectly clear. "Here, then, let us apply our rules. According to them, reality, like every other quality, consists in the peculiar sensible effects which things partaking of it produce. The only effect which real things have is to cause belief, for all the sensations which they excite emerge into consciousness in the form of beliefs. The question therefore is, how is true belief (or belief in the real) distinguished from false belief (belief in fiction)". Briefly this may be answered by saying that the true belief is the one which will be arrived at after a complete examination of all the evidence. "That opinion which is fated to be ultimately agreed to by all who investigate, is what we mean by the truth, and the object represented in this opinion is the real." (Note: "Fate means merely that which is sure to come true, and can nohow be avoided".) The real thus depends indeed upon what is ultimately thought about it, but not upon what any particular person thinks about it. This is clearly brought out in contrast to non-scientific investigation, where personal equation counts for a great deal more. "It is hard to convince a follower of the _a priori_ method by adducing facts; but show him that an opinion that he is defending is inconsistent with what he has laid down elsewhere, and he will be very apt to retract it. These minds do not seem to believe that disputation is ever to cease; they seem to think that the opinion which is natural for one man is not so for another, and that belief will, consequently, never be settled. In contenting themselves with fixing their own opinions by a method which would lead another man to a different result, they betray their feeble hold upon the conception of what truth is. On the other hand, all the followers of science are fully persuaded that the processes of investigation, if only pushed far enough, will give one certain solution to every question to which they can be applied. One man may investigate the velocity of light by studying the transits of Venus and the aberration of the stars;