The entire life of a good Christian is an exercise in holy desire. You do not see what you long for, but the very act of desiring prepares you, so that when God comes you may see and be utterly satisfied.
Suppose you are going to fill some holder or container, and you know you will be given a large amount. Then you set about stretching your sack or wineskin or whatever it is. Why? Because you know the quantity you will have to put in it, and your eyes tell you there is not enough room. By stretching it, therefore, you increase the capacity of the sack, and this is how God deals with us. Simply by making us wait God increases our desire, which in turn enlarges the capacity of our soul, making it able to receive what is to be given to us.
— St. Augustine from Love One Another, My Friends: St. Augustine’s Homilies on the First Letter of John and first posted by Jim Manney on Ignatian Spirituality.