The most powerful form of prayer, and the one which can virtually gain all things and which is the worthiest work of all, is that which flows from a free mind. The freer the mind is, the more powerful and worthy, the more useful, praiseworthy and perfect the prayer and the work become. A free mind can achieve all things. But what is a free mind?
A free mind is one which is untroubled and unfettered by anything, which has not bound its best part to any particular manner of being or devotion and which does not seek its own interest in anything but is always immersed in God’s most precious will, having gone out of what is its own.
Meister Eckhart (Talks of Instruction 2 in Davies, 1994)
quote from Meister Eckhart and Prayer