The call and the aspiration are only first conditions; there must be along with them and brought by their effective intensity an opening of all the being to the Divine and a total surrender.
This opening is a throwing wide of all the nature on all its levels and in all its parts to receive into itself without limits the greater divine Consciousness which is there already above and behind and englobing this mortal half-conscious existence. In the receiving there must be no inability to contain, no breaking down of anything in the system, mind or life or nerve or body under the transmuting stress. There must be an endless receptivity, an always increasing capacity to bear an ever stronger and more and more insistent action of the divine Force. Otherwise nothing great and permanent can be done; the Yoga will end in a break-down or an inert stoppage or a stultifying or a disastrous arrest in a process which must be absolute and integral if it is not [to] be a failure.
Ref: Essays Divine and Human