What Moves Our Love?

I have been reading St. Augustine's Confessions for a class I am teaching on it. One phrase that grabbed me in Book XIII of the Confessions is, "weight moving me is love." 

In Greek thought, the world is made of four elements - Earth, Water, Air and Fire. Earth is the heaviest so it is stuck at the bottom. Water is lighter so it is above earth. Air is lighter still and raises above water. Fire is the lightest for it sends flames heavenward. When St. Augustine says "weight moving me is love", he means that if our love is heavy like earth then it will be stuck in the material-love of this world. On the other hand when our love is light like the fire, it will raise up towards the Heavens where God resides. 

Of course, this lightening of love does not happen by self-effort. Augustine says... 

"By your (God's) gift we are kindled and borne upward, we are set afire and we go... It is your fire, your fire for good, that burns in us as we go up..."

What is the weight that moves our love? What fires our passion and keeps us moving? Is it the fire of the love of the living God or is it the fire of personal ambition, which entangles us in the web of earthly loves?