Humility as the Essential Key to Holiness

Humility must always be doing its work like a bee making its honey in the hive:
without humility all will be lost [...] As I see it, we shall never succeed in knowing ourselves unless we seek to know God: let us think of His greatness and then come back to our own baseness; by looking at His purity we shall see our foulness; by meditating upon His humility, we shall see how far we are from being humble. There are two advantages to this. First, it is clear that anything white looks very much whiter against something black, just as the black looks blacker against the white. Secondly, if we turn from self toward God, our understanding and our will become nobler and readier to embrace all that is good: if we never rise above the slough our own miseries we do ourselves a great disservice. 

–St. Teresa of Avila's "Interior Castle" Page 52-53 Hat tip to St. Peter's List