Sense perception is the standard of truth, or of science in general. The phenomena of the outside world are the standard of physical truths, and man with his many wants is the standard of moral truth. The actions of man are determined by his wants. Thirst teaches him to drink, need to pray. Wants are regulated in the South by southern conditions, in the North by northern conditions. Wants rule time and space, nations and individuals. They induce the savage to hunt and the gourmand to indulge. Human wants give to reason a standard for judging what is good, right, bad, reasonable, etc. Whatever satisfies our need is good, the opposite is bad. The physical feeling of man is the object of moral standards, the object of "practical reason." The contradictory variety of human needs is the basis for the contradictory variety of moral standards. Because a member of a feudal guild prospered in a restricted competition, and a modern knight of industry in free competition, because their interests differ, therefore their views differ, and the one justly considers an institution as unreasonable which the other regards as reasonable. If the intellect of some person attempts to define by mere introspection the standard of reasonableness as a general thing, this person makes himself or herself the standard of humanity. If reason is credited with the faculty of finding within itself the source of moral truth, it commits the speculative mistake of attempting to produce understanding without perceptible objects. The same mistake is to blame for the idea that man is subordinate to the authority of reason, for the demand that man submit to the dictates of reason. This idea transforms man into an attribute of reason, while in reality reason is an attribute of man.