My heart is weak and poorI would guess that the vast majority of people pronounce that last word with a short vowel: "wind," meaning a mass of air moving over the land. Rhyming "find" (long I) with "wind" (short I) would seem to them one of those things poets do, like rhyming "love" and "move." They would understand the variability of wind (air) as a metaphor for our own inconstancy.
Until it master find;
It has no spring of action sure,
It varies with the wind.
In fact, those who read (sing) the text that way are foisting upon it a mixed metaphor. Look at it again. It's easier to see what the poet is doing when you read the text than when you sing it. The metaphor is of a pocket watch. My heart cannot keep proper time in sync with God's heart. My action (in both a behavioral and in a watchmaker's sense) varies with how intensely and regularly I wind it, which means, when I feel like it. So "there is no spring of action sure" within me until God becomes my master and imparts his motion to my soul. That means the proper pronunciation here is "wind" (long I), meaning the act of winding a watch, and "find" and "wind" rhyme regularly in the text.
The question then becomes, how much hangs upon my properly understanding the text I am singing? As far as hymns go -- something that C.S. Lewis famously called "second-rate poetry set to third-rate music" -- probably not much. The idea of my inconstancy, my inability to keep up with God, is maintained whichever way I sing or understand the word, "wind."
But is the poem I read the same as the poem the poet wrote? If I consistently pronounce the word "wind" with a short I, if I construe it to refer to weather rather than machinery, I am not just privileging my reading of the text, I am rejecting the poet's reading of the text. In effect, I am now reading/singing a different poem. And when we get to things more consequential than a Hymn of Response sung after a sermon, then it starts to matter a lot more.
Back in seminary, I was required to take a course in Exegesis of the Greek New Testament. Exegesis means "drawing out," and it is the discipline of understanding what, in fact, the text of the New Testament actually says. Eisegesis is the action of putting your own meaning into the text. Sometimes this can make an edifying sermon, but it can also take you to peculiar places.
I was once at an Order of the Arrow weekend, and a local preacher was called in to do chapel for us. He was an earnest man, probably holier than I'll ever be. But I can still remember him speaking to the Arrowmen about "holding fast what is good" (1 Thessalonians 5:21). He explained carefully to them that what that meant was that when something good comes around and you recognize its value, you need to grab it quick before it gets away. Now, that'll preach, as they say, but needless to say, I was stunned at his misunderstanding of the text. "Hold fast" means to hold securely, to fasten onto something. It has nothing to do with snatching at something so as not to miss your opportunity. The preacher had failed to even construe the English translation correctly, let alone the Greek of the NT. That's an example of eisegesis.
Some people who are guilty of eisegesis are serious students of the Bible, and their weird ideas come out of reading what they think is a self-authenticating text. The meaning they foist upon it must be what the Bible means because the Bible says what they're saying. But five minutes' study will show you that that could not possibly be what the author of the Biblical text meant. Doesn't matter, they'll say. "The Bible says . . ."
Other people are guilty of eisegesis because they have already decided what they want the Bible to say, and they're determined to make it say it. Or, if they can't get it to say what they want, they'll explain the text by explaining it away. This is common among those who are on the other end of the religious spectrum -- the liberals, the progressives, the ideologues for whom political theory has taken the place of the canon and the creeds.
And we find this same wrangle in another area of our life as a nation. Those who believe in a "living constitution" are opposed by those who, to one degree or another, are called "originalists." Think Stephen Breyer vs. Antonin Scalia. The originalists say we must at least understand what the people who wrote and adopted the U.S. Constitution meant by it, before we proceed to decree what it means in the case before us. The proponents of the "living constitution" believe that any meaning they can derive from the text, sanctioned by whatever thought is in vogue among their fellows, IS what the text means. As Charles Evans Hughes said, "the Constitution is what the judges say it is," which effectively means whatever five people in black robes can agree upon, regardless of the actual words of the document they claim to be construing. Indeed, all five justices can write separate opinions disagreeing with each other in all kinds of particulars, but their common vote on which side won the appeal before them becomes authoritative.
As someone who has great respect for the word -- derived ultimately from him who is called the Word of God, the Logos, the Reason behind the Universe -- I don't want to know just what so-and-so means by the words of a poem, or a Scriptural passage, or the constitution, or even a private communication. I want to understand what the author intended. I am then free to disagree with that author, to oppose my words to his words, to write a savage review, or even just to ignore what has been written and go on my merry way. But it is a terrible act to deliberately misconstrue someone else's words. It is a violation of that person, and a denial of our common life together. And it will lead me into all kinds of narcissistic follies as I go about making up my own reality to suit myself.
Which is where a lot of our society is these days, I'm afraid. Me, I want teachers who teach us how to read the poem the poet actually wrote, preachers who preach what the Bible actually says, and judges who decide cases based upon the law as understood by those who debated it, voted on it, and bequeathed it to us.