There is not an unholy belief nor an unwholesome theory which cannot be bolstered up by means of apparent facts. For example, that monstrosity of Puritan thought known as “Salem Witchcraft” was substantiated by facts honestly observed. Again, having made up his mind that it is going to be “so and so,” the statistician goes out into the highways and byways and gathers the facts which vindicate his judgment. Further, the democrat finds that the _majority_ of the voters are democrats; while the republican is confident that _two-thirds_ of the voters are for republicanism. Here again is the fallacy springing from a preadjustment of attention. _We see what we want to see._ Only the highly trained observer is able, with impunity, to make use of preadjusted attention, and even with him, it is not easy to remove from the situation _belief_ and _prejudice_. The true observer undertakes his work with his mind open to _anything_ which the eye may bring him, though it may topple into the dust his dearest theory and most cherished belief; he proceeds――_the mind a “clean white page.”_ (2) The “observed” and the “inferred” confused. This error has already received some attention. It may be remarked further, however, that, psychologically considered, observation is a matter of interpreting the new by means of the old. Of necessity the interpretation, whatever it may be, will assume the complexion of the particular “old knowledge” which the mind is able to use. In short, a man _will_ see what his previous environment has _trained_ him to see; the conscientious gardener sees the weeds, whilst the artist may see nothing but the flowers. It follows, therefore, that all observation must be largely a matter of inference based on experience. In looking at the moon, for example, all I actually see is a patch of color; the form and distant location of the moon being a matter of experience. The inference referred to in this heading is not that which is _necessary_ for perception, but that which is _suggested_ by perception. To illustrate: It is icy; three men are running for a car; Smith raises his arm; Jones slips to the ground; and Brown testifies, that “Smith knocked Jones down.” Brown _observed_, that Smith assumed the proper attitude and that Jones conveniently went down at the right time; and then _inferred_ the rest. (3) Ignoring the exceptions.