We have the same method of testing our power in regard to the _prevention_ of desires and emotions. No matter how painful or inappropriate may be the desires and emotions of any mind, it is acting _perfectly_ when it goes to the full extent of its power to extinguish or to control them according to the rules of rectitude. If it wills to have them otherwise, and uses the appropriate modes to have them so, this is all it has power to do. In reference to _external actions_, there are an infinite variety of circumstances that must decide the character of actions as right or wrong. An action which is wise and benevolent in one set of circumstances becomes foolish and selfish in another combination. More than half the questions of right and wrong action are to be decided as to their character by the surrounding circumstances, while no mind but the one that is infinite and omniscient can pronounce with certainty on actions whose character is dependent on circumstances and probable future results. What, then, is the limitation of power in these cases? How can we know when we act as nearly right as it is in our power? In the first place, we can have the high evidence of consciousness that our chief end in life is _to act right_ in all things. In the next place, we can know certainly whether there is any thing more that we can do to find out what the right course is. When we have decided that we have done all we can in the given circumstances, and then are conscious that we choose _what we believe to be right_, or _that which has to our mind the balance of evidence in its favor as right, we act perfectly_; that is to say, we have reached the full measure of our power in voluntarily acting right. But, besides this evidence, that rests mainly on internal consciousness of the nature of our volitions, we have other evidence to guide us. It has been shown in the previous pages how our thoughts, and desires, and emotions are all dependent on the generic purposes of the mind. Whatever is the _chief end_ of life is the object which excites the strongest interest and calls forth the deepest emotions. Therefore, when a mind has chosen _to act right_ as the chief end, all its tastes, desires, and emotions become conformed to this purpose. Whatever is seen as tending to promote this end is more desired and valued than any thing else. Whatever is seen to interfere with this is regarded with dissatisfaction. This being so, a mind that is controlled by a ruling purpose to act right finds those persons and places the most congenial and agreeable who can lend the most aid in pointing out all that is wrong in thought, word, or deed, and in helping, by instruction, sympathy, and example, to do right. One great test, then, of the existence and strength of such a ruling purpose is the manner in which those are regarded who are most interested in finding out and doing what is right themselves, and in aiding others to do so.