The Soul is the life. There is some form of life even in inanimate objects. The molecules within all objects constantly move. This shows that there is life in there.
The life of a plant is higher than the life of a stone. "Higher" here means that Hashem does not hide as much in the life of a plant as He does in the life of an inanimate object. Not only does life move inside a plant, it causes the plant to grow, to live, and to die. But even in a dead plant there is some form of life as surely there are molecules moving in there, too.
Life in an animal is higher than the life in a plant. Animals have some form of will. They make conscious choices. They have intentions, likes and dislikes. They become tired; cry out when they are wanting.
Even higher than the life of an animal is the natural soul of man. Mankind has freewill, he (or she) can choose between good and evil. This soul allows man the advantage of speech.
Still higher than the natural soul of all mankind is the additional, spiritual soul that Hashem has placed in every Jew. This spiritual soul gives the Jew a tremendous advantage, but it also brings an even greater responsibility. Hashem has assigned the Jewish people to be a nation of priests, and to share His light with the world. In order to fulfill this mission He has placed within us this holy soul. There is nothing manifested anywhere that is higher than this soul. This soul is an actual portion, or breath of Hashem from on High. But even this holy soul has come about only after Hashem has hidden Himself in order to make that soul. "The soul you have given within me is pure. You have created it, You have formed it, You have breathed it into me, and you preserve it within me…."[i]
All souls vivify, enliven the bodies they are placed in. That is their function. But this holy soul of a Jew does not physically vivify the Jew. It is placed there to make it easier for the Jew to become aware of Hashem's Presence. But, this added awareness of Hashem does not come automatically, not even to the Jew. Awareness of Hashem must be sought, desired, yearned for. If the Jew ignores this spiritual gift the gift will sleep within him. But no matter how long or how hard it sleeps, it can be awakened in a moment. Wake up…it's time to go to work.
[i] early morning prayer