These are matters to be found within the domain of reality, susceptible of demonstration or refutation by the ordinary operations of science; entirely true or entirely false, and, therefore, in the former case, not liable to become obsolete. We proceed after the manner of the investigator of nature. We, too, have our dissecting knife and microscope, and we have an advantage over the student of nature in this, that the self-observation of the body is exceedingly limited, while that of mind is almost unlimited. There are other respects, however, in which he has the advantage over us. When he wishes to study a given species, he may make a hundred or a thousand experiments, and use a hundred or a thousand individuals for his purpose. Hence, he can easily control each separate observation, and distinguish the exception from the rule. But, how many nations are there which we can make use of for purposes of comparison? Their very fewness makes it all the more imperative to compare them all. Doubtless, comparison cannot supply the place of observation; but observation may be thus rendered more thorough, many-sided, and richer in the number of its points of view. Interested alike in the differences and resemblances, we must first form our rules from the latter, consider the former as the exceptions, and then endeavor to explain them. (_Infra_, § 266). Section XXVII. Advantages Of The Historical Or Physiological Method. The thorough application of this method will do away with a great number of controversies on important questions.(176) Men are as far removed from being devils as from being angels. We meet with few who are only guided by ideal motives, but with few, also, who hearken only to the voice of egotism, and care for nothing but themselves. It may, therefore, be assumed, that any view current on certain tangible interests which concern man very nearly, and which has been shared by great parties and even by whole peoples for generations, is not based only on ignorance or a perverse love of wrong. The error consists more frequently in applying measures wholesome and even absolutely necessary under certain circumstances, to circumstances entirely different. And here, a thorough insight into the conditions of the measure suffices to compose the differences between the two parties. Once the natural laws of Political Economy are sufficiently known and recognized, all that is needed, in any given instance, is more exact and reliable statistics of the fact involved, to reconcile all party controversies on questions of the politics of public economy, so far, at least, as these controversies arise from a difference of opinion. It may be that science may never attain to this, in consequence of the new problems which are ever arising and demanding a solution. It may be, too, that in the greater number of party controversies, the opposed purposes of the parties play a more important part even than the opposed views.