You stand at the edge of a canyon or ravine. Facing the opposite wall, you cup your hands to your mouth and call out: “Hellooo!” Then you wait for your own voice to bounce back to you in response, once, twice, maybe more, the echoes getting softer each time. If you’re in an especially playful mood, you might even turn it into a short conversation. But there’s just something fascinating about an echo, and we don’t often get a chance to experience in such an obvious way.

If you’re a bat, however, there’s nothing particularly remarkable about this.

Bats navigate by echolocation: a form of biological radar, if you will. As t hey fly, they continually emit squeaks, most of which are well beyond the range of human hearing. They read how the sounds bounce off objects in their environment, allowing them to avoid obstacles and find dinner. Their hearing is so sensitive that they are able to find even the smallest of flying insects — in the dark.

(By the way, the phrase “blind as a bat” isn’t really fair to bats. They can see perfectly well, but that’s not terribly helpful for navigating or finding food at night. Their echolocation is essentially their version of “night vision,” which we lack. Thus, it would make more sense for bats to joke about being “blind as a human,” at least in the dark.)

I want to use the phenomenon as a metaphor for understanding something that occurs repeatedly in Scripture, something biblical and literary scholars call intertextuality (the term was coined by philosopher Julia Kristeva). Basically, intertextuality refers to the fact that the meaning of one text depends to an extent on the meaning of an earlier one that is hopefully known to the reader — something like a literary in-joke.

My wife and I, for example, have a tendency to quote lines from movies and shows we’ve seen together. When our kids were young, we watched the family movie Babe together, a story about a remarkable pig raised by sheepdogs. In a key moment in the story, the farmer tells Babe proudly, “That’ll do, pig.” Today, as a final flourish on a household task done well, I’m apt to say to my wife, “That’ll do, pig”; often, she repeats it back to me.

Imagine how that phrase might be taken if she hadn’t seen the movie with me.

These back-references can be intentional and explicit, as in a direct quotation. It can be intentional but less explicit, as in a paraphrase. And it can be unintentional, as when prior texts so shape a writer’s imagination that echoes of the past can be heard in the writer’s work even when they’re not intended.

You can see this in Scripture (where there are no copyright laws or worries about plagiarism to get in the way of the free use of other texts!). Jesus and Paul, for example, frequently quote the Psalms and prophets. Sometimes, this is made crystal clear by prefacing the quote with the phrase, “As it is written.” But such a lead-in isn’t always given. Moreover, the referenced texts may be nothing more than short phrases, and paraphrased to boot.

Does it really matter for interpretation and understanding?

Here’s an example from the beginning of Psalm 86. In the New Revised Standard, the psalm opens with these words: “Incline your ear, O LORD, and answer me, for I am poor and needy.” The New Living Translation, however, reads, “Bend down, O LORD, and hear my prayer; answer me, for I need your help.” From a purely functional point of view, there’s nothing wrong with the NLT: the psalmist is indeed praying for God’s help.

But the translation misses the way the phrase “poor and needy” echoes the language and imagery of other psalms. Together, these psalms teach that God is the champion of the destitute and oppressed who suffer injustice. Thus, “I need your help” puts the emphasis on the psalmist’s predicament, but the echoes heard in “I am poor and needy” point to the mercy of God.

Why am I telling you this? Because our next passage in Paul’s letter to the Philippians is a bit of a strange one. The practical purpose of what he’s saying is clear enough, but the sentences seem to meander a bit, jumping from one idea to another. One way to understand this is intertextuality. Given his history and training, Paul’s mind is steeped in Old Testament texts and stories. These shape how he sees and responds to the Philippians’ situation; it comes out in his language and imagery.

Is this intentional or unintentional? If he were writing primarily to fellow Jews, I’d have no question. But he’s writing to a primarily Gentile audience, and there’s no way to know how much they knew of the ancient stories. Still, even if references to the Old Testament simply flow from Paul because he can’t help himself, noticing the intertextuality helps deepen our understanding of Paul’s words.

How? If I may suggest it, what Paul is doing is echo-location: he echoes the Old Testament in order to locate the Philippians’ current situation in the larger, ongoing story of God. We’ll explore how in upcoming posts.