Human beings are equipped with two great powers: reason and will.
Reason is the light which specifies the fate of the human soul in this life. It is considered the representative of our factual personality and is a shining light that illuminates the pages of life. Therefore, without the guidance and supervision of reason we cannot advance on the ever-complex avenues of life.
We are required to endeavor to control the various feelings which we find in ourselves, thus preventing excess or underestimation of these feelings. Reason is the power that demonstrates to us the proper method of applying healthy feelings, and prevents us from allowing emotions to lead us blindly.
In reality, if the light of reason shines on our feelings, it is then guaranteed that the rays of happiness will illuminate our lives. On the contrary, if we are enslaved by our cravings we will be weakened, which would result in our defeat in all walks of life.
Will is one of the most influential moral factors and the strongest way of achieving good intentions and noble hopes. It has strong correlation to the basis of our happiness. Our will also protects our personality from the reach of filth and the lowliness of life. A strong will is a determining factor in a happy life; it allows us to resist events which can have influential consequences on our lives.
The more effort we implement toward strengthening this vital power, the more vigor we achieve in order to obtain moral excellence and to avoid corruption. Our souls, then, become tranquil and protected from disarray.
There is a beautiful definition of reason that also implies its balance: Reason is the organizing power. This power, which like a new type of steering mechanism for cars, prevents both men and women from colliding with each other. It is a system which absorbs great shocks which result from sudden collisions or road irregularities; it offers passengers comfort and assurance even on the toughest roads.
Source: Youth and Morals