But it is often the case that we feel the strongest desire for that which is not _best_ for us. Thus, when sick we have tempting fruit and nauseous medicine before us, with power to choose either. Our intellect decides that the medicine is best for us, but our strongest desire is for the fruit. In such a case we have power to choose _either_ that which excites the strongest desire or that which the intellect decides to be _best_, even when it does not excite the strongest desire. This power is the chief feature of a _rational_ mind in distinction from an irrational mind. And the belief that we have this power is to be placed as one of the principles of common sense, because all men talk and act as if they believe they possess this power. And if any person were to talk and act as if he did not believe that he had power to choose in either of these two ways, he would be regarded as having lost his reason. Reason, or Common Sense. Of the thoughts which continually pass through the mind, we find that some are attended with a feeling of the real existence of the objects of our thoughts, and others are not so attended. For example, we may think of a man with a certain form carrying a dagger and going to commit murder, and with this, a feeling that no such thing is really existing. Again, we may have this same idea attended with the conviction that it is a reality. This feeling of the _reality_ of the objects of our thoughts is called _belief_, or _faith_. Our minds are so made, that we necessarily believe not only that things _are_ really existing at the present time, but that things _will_ occur that are not now in existence. For example, we believe the sun will rise to‐morrow morning in another place nearer toward the north or south than it did the present morning. We believe the tide will rise higher or lower on a coming day than it did the present day. And thus multitudes of events are believed to be in the future. Those things which really do or will exist, in distinction from those we may think of but which do not and will not exist, are called _truths_, or _realities_. All our comfort and happiness depend on our believing _the truth_, meaning by truth the _reality_ of things. To believe that things exist when they do not, or that things are not existing when they are, involves certain pain, disappointment and mistake. Our great safeguard from this is that part of our mental organization called _reason_, or _common sense_. This, as has been shown, consists in the necessary belief of certain truths by all men. The _test_ by which these truths are identified and distinguished from all other knowledge, is the fact that usually all men talk and act as if they believed them, and that when they fail to do so, they are regarded as having “lost their reason.” The truths thus necessarily believed are the foundation of the process called _reasoning_, which is a mode of establishing other truths by the aid of those already believed.