Lilies that fester

They that have power to hurt and will do none,
That do not do the thing they most do show,
Who, moving others, are themselves as stone,
Unmoved, cold, and to temptation slow,
They rightly do inherit heaven's graces
And husband nature's riches from expense;
They are the lords and owners of their faces,
Others but stewards of their excellence.
The summer's flower is to the summer sweet,
Though to itself it only live and die,
But if that flower with base infection meet,
The basest weed outbraves his dignity:
For sweetest things turn sourest by their deeds;
Lilies that fester smell far worse than weeds.
-Shakespeare, Sonnet 94

This is one of the enigmatic sonnets where we don't really know who's the subject. However, I find the last four lines extraordinarily perceptive about some of the moments in my own life.