Father Gabriel in his book on St. John of the Cross, writes this:
Love sujects the love to the object loved; it make him love all that the beloved will; it transforms the willl of the lover into the will of the beloved, so that it is as though there were no longer two will but only one: that of the beloved, to which the lover conforms himself completely.
Father is quoting St. John and paraphrasing a longer section. The first stage of the purification of the sensible part of the soul is something which most of us understand. Yet, how many times, do we start and stop this process, going backwards because we either lack courage or generosity, or, simply, love?
The lover, as Father points out, responds quickly to a suggestion or question. In fact, the true lover anticipates the requests or desires of the beloved. And, as he states, "To do things thoroughly, not by halves; such is the outstanding characteristic of Carmelite spirituality."
Part of the poem, only one of St. John's from the Ascent, reads
Strive always not after that which is most easy, but after that which is most difficult;
Not after that which giveth pleasure but after than which giveth none;
Not after that which ministers repose but after that which ministers labour;
Not after great things but after little things;
Strive not to desire anything but rather nothing.
Without this purification, true contemplation cannot happen. It is the empty heart which can receive God.