What canst thou hear?
Quakers are fond of "What canst thou say?", a question George Fox asked that was key to converting Margaret Fell, a powerful early Quaker and much later Fox's wife. It reminds us that we too are active participants, fitting tightly with Quakerism's abolition of the laity which makes us all ministers.
Sometimes I see it expanded further to:
You will say, Christ saith this, and the apostles say this, but what canst thou say?
That seems to suggest an opening for anything, even potentially a rejection of the prior revelations on which early Quakers built their world. Going a step further, however, to explore the surrounding story in Fell's telling of her convincement, reveals that this is not a wholesale rejection. Instead, it is an enormous step toward inclusion and construction:
And so [Fox] went on, and said how that Christ was the Light of the world, and lighteth every man that cometh into the world, and that by this Light they might be gathered to God, etc. And I stood up in my pew, and I wondered at his doctrine, for I had never heard such before.
And then he went on, and opened the scriptures, and said The scriptures were the prophets' words, and Christ's and the apostles' words, and what as they spoke they enjoyed and possessed and had it from the Lord.
And said, "Then what had any to do with the scriptures but as they came to the Spirit that gave them forth? You will say, Christ saith this, and the apostles say this, but what canst thou say? Art thou a Child of Light, and hast walked in the Light, and what thou speakest is inwardly from God, etc. ?"
This opened me so, that it cut me to the heart, and then I saw clearly we were all wrong. So I sat me down in my pew again, and cried bitterly : and I cried in my spirit to the Lord, "We are all thieves, we are all thieves, we have take the scriptures in words, and know nothing of them in ourselves." (The Beginnings of Quakerism to 1660, 101, from Margaret Fell's account.)
"And what thou speakest is inwardly from God" clarifies what is to be spoken, what thou canst say. Speaking in this instance requires learning from the inward Light, listening before speaking. What "thou" says here isn't coming directly from "thou", but from "thou" with assistance from God.
Margaret Fell's reaction to Fox telling her this isn't relief that she can say whatever she likes, but rather the painful realization that she has been following the wrong path, and she weeps in her pew.