O the blessed chemistry of heaven!

(John Flavel "The Method of Grace")

The Lord makes use even of your sins and
infirmities to do you good. By these, He . . .
  humbles you,
  beats you off from self-dependence,
  makes you admire the riches of grace,
  makes you long more ardently for heaven,
  causes you to entertain sweeter thoughts of death.

Does not the Lord then, make blessed fruits to spring
up from such a bitter root? O the blessed chemistry
of heaven—to extract such mercies out of such miseries!