"This restful travail"

From Evelyn Underhill's Mysticism: A Study in Nature and Development of Spiritual Consciousness:

It remains a paradox of the mystics that the passivity at which they appear to aim is really a state of the most intense activity: more, that where it is wholly absent no great creative action can take place. In it, the superficial self compels itself to be still, in order that it may liberate another  more deep-seated power which is, in the ecstasy of the contemplative genius, raised to the highest pitch of efficiency.

"This restful travail," said Walter Hilton, "is full far from fleshly idleness and from blind security. It is full of ghostly work but it is called rest, for grace looseth the heavy yoke of fleshly love from the soul and maketh it mighty and free through the gift of the holy ghostly love for to work gladly, softly, and delectably. . . . Therefore is it called an holy idleness and a rest most busy; and so is it in stillness from the great crying and the beastly noise of fleshly desires."