In regard to this we have two sources of evidence: first, the mental consciousness of the acting mind itself, and, next, the results of its action. In regard to the first, every mind, in reference either to its mental states or external deeds, can have as much certainty as to the extent of its power as it can of any thing. If we _choose_ to feel in a given way, or to perform a given act, and what we choose does not follow, we are certain we have no power to do the thing. All the idea of _power_ we have is that volition is followed by the result chosen. All the idea we have of _want of power_ is that the result chosen does not follow the volition. Every mind, then, in regard to _every specific volition_, has the most perfect of all evidence as to the extent of its powers in its own experience. But the question is a more difficult one in reference to a _generic governing volition_. A perfectly acting mind, according to our definition, is one that has formed a generic governing volition to _feel and act right_ in all respects; that is, it decides that the chief end of existence shall be to promote the greatest possible happiness with the least possible evil, in obedience to all, physical, social, and moral laws of the Creator, so far as it is within the reach of its powers. Now, as to this simple act of choice, a mind can have the highest possible evidence in its own consciousness. The only question of difficulty would be as to _the extent_ of its powers to carry out this decision, and the correspondence of all its subordinate volitions with this generic purpose. To ascertain the truth on this point, let us suppose a mind that has the highest evidence (that of internal consciousness) that it has formed such a purpose. Then comes a case where a subordinate decision is to be made--say it relates to the existence of a certain _feeling_ or _emotion_, such as love, fear, gratitude, or sorrow. It has been shown that these emotions are not to be evoked into existence by a simple act of will. The mode by which the mind controls its own desires and emotions is set forth on page 162. If, then, the person chooses to do _all that is in its power at the given time_ to awaken these emotions, its action is _perfect_ in this respect: it has fulfilled the measure of its power. It reaches the limit of its power when it can find nothing more that an _act of choice_ will secure that it perceives will tend to accomplish the end chosen. That is to say, at each given moment, when a mind is aiming to know what is right, and to do it, if it has done all it perceives can be done by any act of will toward this end, then its decision or mental action is _perfect_; it is as good as is possible in the nature of things.