By George Herbert
As men, for fear the stars should sleep and nod
And trip at night, have spheres suppli'd;
As if a star were duller than a clod,
Which knows his way without a guide:
Just so the other heav'n they also serve,
Divinity's transcendent sky:
Which with the edge of wit they cut and carve.
Reason triumphs, and faith lies by.
Could not that wisdom, which first broacht the wine,
Have thicken'd it with definitions?
And jagg'd his seamless coat, had that been fine,
With curious questions and divisions?
But all the doctrine, which he taught and gave,
Was clear as heav'n, from whence it came.
At least those beams of truth, which only save,
Surpass in brightness any flame.
Love God, and love your neighbor. Watch and pray.
Do as ye would be done unto.
O dark instructions; ev'n as dark as day!
Who can these Gordion knots undo?
But he doth bid us take his blood for wine.
Bid what he please; yet I am sure,
To take and taste what he doth there design,
Is all that saves, and not obscure.
Then burn thy Epicycles, foolish man;
Break all thy spheres, and save thy head.
Faith needs no staff of flesh, but stoutly can
To heav'n alone both go, and lead.
Herbert was a contemporary of philosopher René Descartes who, allegedly, was looking for a way to ground the Christian faith in reason, but, in a striking instance of the Law of Unintended Consequence, set in motion the so-called Cartesian Revolution, a movement away from faith to rationalism. Herbert, aware of Descartes' growing influence, may have penned this poem in response.
He begins with astronomers' efforts to map the skies and develop constructs for the movement of the stars. Presumably, they did so to serve "Divinity's transcendent sky," the world of spiritual realities. They "cut and carved" with human wit (wisdom), but only darkened wise counsel with words. Reason triumphed and faith was laid aside.
Could not the wisdom that "broacht" (opened) the wine at Cana have supplied an explanation for the miracle and "thickened it with definitions"? Jesus could have, but chose not to, nor has he explained everything else that puzzles us. The universe is shrouded in paradox, contradiction and mystery, a phenomenon Rutgers' philosopher, Colin McGinn, calls the Mysterion Position: the notion that our minds are simply incapable of knowing all there is to know. There are absolute limitations to the human intellect that cannot be overcome.
God does draw lines, but, as George MacDonald said, his lines are very thin, and often invisible. To draw hard lines everywhere, therefore, is futile. Worse yet, hard lines divide us and become occasion for acrimonious debate. Hence the old cliché, "No one damns like the orthodox."
For this reason, as I've grown older, my list of absolutes has grown correspondingly shorter. There are essentials of which I have no doubt, but much is mystery to me. I ponder these puzzles periodically, but they don't bother me anymore. I know "there are more things in heaven and earth, than are dreamt of in (my) philosophy." This is what "saves my head."
This is the sentiment echoed by George MacDonald's father in a letter to his son about the long-standing, divisive debate over God's sovereignty and our free will: "[I cannot] bear to see that which is evidently gospel mystery torn to pieces by those who believe that there is no mystery in the Scriptures and therefore attempt to explain away what it is evidently for the honor of God to conceal. I see so much of mystery in nature, and so much of it in myself, that it would be proof to my mind that the Scriptures were not from God were there nothing in them beyond the grasp of my own mind." 
That being said, our Lord did not leave us in the dark with regard to the things that matter, but has given instruction that is "clear as heav'n from whence it came." He has revealed "beams of truth, which only save (sanctify)." These he enumerates: "To love God, and love your neighbor. Watch and pray. Do as ye would be done unto"-simple directives Herbert describes, with subtle irony, as Gordion knots, and "dark instructions; ev'n as dark as day!" To love and to pray and to do good to others-a few things I know I must do. This is the more excellent way.
Mark Twain said, "It's not the things I don't understand in the Bible that concern me, but the things I do understand." Exactly. It is my prayer that I, at last, may do those things that matter.
 spheres: Concentric hollow globes that were thought to rotate around the earth and carry heavenly bodies, according to the Ptolemaic astronomy of Herbert's day.
 lies by: is unused
 broacht: opened
 jagg'd: torn
 Epicycles: In Ptolmaic astronomy, each of the seven planets was thought to move in a circle, the center of which rotated around the earth. Circles within circles, ad infinitum.
 Another contemporary, Blaise Pascal, said, "I cannot forgive Descartes. In all his philosophy he would have been quite willing to dispense with God. But he had to make Him give a fillip to set the world in motion; beyond this, he has no further need of God."
 In a letter to his son, May 31, 1850
 The Gordian Knot is a legend associated with Alexander the Great and is a metaphor for an intractable problem. The irony lies in the fact that this "knot" can be untied by anyone and the darkness of these instructions is "as dark as day(light)."
 Mark Twain and Scottish preacher and poet George MacDonald were friends. I do hope MacDonald's gracious Jesus, at some point, found his way into Mark Twain's heart.
 Cf., Philippians 1:10. Paul's verb, diaphero, here translated "matter," means, "to make a difference."