The Lamp of the Body

Compared to the verses that surround it, Matthew 6:22-23 is hard to understand:

Mt 6:22–23 “The eye is the lamp of the body. So, if your eye is healthy, your whole body will be full of light; but if your eye is unhealthy, your whole body will be full of darkness. If then the light in you is darkness, how great is the darkness!”[1]

It is not immediately apparent how the eye is the body’s lamp, or in what sense the eye was said to be healthy/unhealthy, or how a healthy eye results in the body being full of light, or how a body can be full of light at all. Our natural instinct when reading this section of chapter six is to concentrate on the familiar verses that come before (“store up for yourselves treasures in heaven”) or after (“you cannot serve God and wealth”) because they’re more easily understood. The passage in question appears unrelated to its surrounding context; it’s as if Christ began in v. 19 on the topic of the disciple’s relationship with the temporary things of life and then went off on a short tangent before coming back to his original topic. Our aim is to understand what Christ wanted to communicate in these two verses.

The Sermon on the Mount was given near Capernaum in the region of Galilee in the first half of the first century AD. His audience[2] would have had a mix of Jewish and Greek backgrounds and would have understood Christ’s words through the prism of these worldviews. Christ did not speak into the air; he aimed to be understood. As such he’d have spoken to them in terms they’d have understood. It is therefore instructive to try to understand the passage as they would have.

Christ began this section of the Sermon on the Mount with the statement, “The eye is the lamp of the body.” The phrase is difficult; after all, the eye is not the lamp of the body – it isn’t a lamp at all. How then are we to interpret it? We should avoid the temptation to immediately seek a “spiritual” understanding, endeavouring rather to understand it as the initial audience would have.

The Greek understanding of the mechanics of vision was that of extramission, i.e. that the eye was a lamp that shone light outward in all directions.[3] Theophrastus, a Greek philosopher of the 4th & 3rd centuries BC, agreeing with Plato[4] wrote, “The eye obviously has fire within, for when one is struck this fire flashes out.[5] Empedocles writing in the 5th century wrote, “As when a man, about to sally forth, prepares a light and kindles him a blaze of flaming fire against the wintry night, in horny lantern shielding from all winds; though it protect from breath of blowing winds, its beam darts outward, as more fine and thin, and with untiring rays lights up the sky; just so the fire primeval once lay hid in the round pupil of the eye, enclosed in films and gauzy veils, which through and through were pierced with pores divinely fashioned, and thus kept off the watery deeps around, whilst fire burst outward, as more fine and thin.”[6] It was the common Greek view that the eye was the lamp of the body in a physiological sense.

Jewish culture was no different, particularly in Galilee due to its Hellenization – Greek ideas had strongly influenced the Jews of the north of Israel.[7] It is also worth recognising that scripture links the eye with flames and torches: “On the twenty-fourth day of the first month, as I was standing on the bank of the great river (that is, the Tigris), I looked up and saw a man clothed in linen, with a belt of gold from Uphaz around his waist. His body was like beryl, his face like lightning, his eyes like flaming torches…” (Da 10:4–6). In Zechariah we find the same idea: seven lamps seen in a vision are said to represent the eyes of God (Zech 4:2,10). That the eye was a lamp was a widespread belief in the Greek and Jewish Galilean world Christ moved in.

Due to this widely held view Christ’s audience would have understood his opening phrase in a purely physiological sense. They would have responded to the phrase “The eye is the lamp of the body” in the same way that we would respond to the phrase “The eye is the organ of vision” – we understand it physiologically.

With extramission now planted in their minds Christ’s audience would have been surprised at what came next: “if your eye is healthy, your whole body will be full of light.” The reason for their surprise is that the eye was thought to shine rays out of the body, not into the body. However in this case it is the body that is filled with light, not the person’s environment; thus the eye was shining inward. Immediately the audience was transported from the physiological to the metaphorical.

The Galilean audience would have immediately understood what Christ meant them to understand when he spoke of the “unhealthy eye.”[8] The unhealthy eye was an idiom indicating “one that looks with envy or jealousy upon other people” that would have been familiar to Christ’s audience.[9] This usage can be found earlier in the gospel in the parable of the labourers in the vineyard where the term unhealthy eye has been translated as ‘envious’:

Mt 20:15 “Am I not allowed to do what I choose with what belongs to me? Or are you envious because I am generous?”

This idiom should not be all that foreign for English-speaking people today – an ocular idiom for jealousy is common in modern English: the “green eyed monster” or the “jaundiced eye.”[10]

Contrasted with the unhealthy eye in this antithetical parallelism is the healthy eye. The healthy eye stood for the opposite of envy: contentment[11] or generosity.[12] This content and generous spirit was said to fill the body with light. Conversely jealousy and envy filled the body with darkness. The darkness referred to was moral darkness, explained by Paul as the state of the unbeliever and the godless in his letter to the Ephesians:

Eph 5:8–9 “For once you were darkness, but now in the Lord you are light. Live as children of light— for the fruit of the light is found in all that is good and right and true.”

Having worked through the language of these two verses and seen how Christ was speaking of jealousy, and contentment or generosity, we find that he had not gone off on a tangent as we may first have thought when we read the passage. Instead we see that there is a natural progression of ideas on the topic of the disciple’s relationship with the temporary things of life, vv. 22-23 fitting perfectly into that context.

The verses that come before (vv. 19-21) warn us not to store up treasures on earth but in heaven – one will not last but the other will last forever; most importantly, “where your treasure is, there your heart will be also.” The next two verses continue the theme: don’t value or concern yourself with someone else’s things (e.g. wages, material possessions, family situation, education, home, etc) because they will have a negative moral impact. Instead, the opposite will be true if we are content and generous with what we have. The theme is wrapped up in the verse that follows (Matt 6:24): you cannot serve God and wealth; there’s a choice to be made.

Each of this section’s three parts has a positive and negative aspect and together they make up a comprehensive approach to temporary matters for the disciple:

TeachingPositive aspectNegative aspect
Treasure stores (vv. 19-21)Store up treasure in heavenDon’t store up treasure on earth
Lamp of the body (vv. 22-23)Be content/generousDon’t be envious
Two masters (v. 24)Love GodDespise Wealth

Having been transported from the physiological to the metaphorical Christ had given his audience cause for introspection. We too can learn from this section of the Sermon on the Mount and could do little better than to reflect on the model Paul gave Timothy in which he linked contentment with godliness, and the desire to be rich with ruin and destruction:

1 Ti 6:6–9 “Of course, there is great gain in godliness combined with contentment; for we brought nothing into the world, so that we can take nothing out of it; but if we have food and clothing, we will be content with these. But those who want to be rich fall into temptation and are trapped by many senseless and harmful desires that plunge people into ruin and destruction.”


  1. Unless noted otherwise all scripture references from The Holy Bible: New Revised Standard Version (Nashville: Thomas Nelson Publishers, 1989)
  2. It appears that Christ’s audience grew over the course of the sermon. He began speaking to just the disciples (Mt 5:1) but by the time he reached his conclusion he was speaking to a crowd (7:28).
  3. François Bovon, Luke 2: A Commentary on the Gospel of Luke 9:51–19:27(ed. Helmut Koester; trans. Donald S. Deer; Hermeneia—A Critical and Historical Commentary on the Bible; Minneapolis, MN: Fortress Press, 2013), 147–148. See also Ulrich Luz, Matthew 1–7: A Commentary on Matthew 1–7 (ed. Helmut Koester; Rev. ed.; Hermeneia—a Critical and Historical Commentary on the Bible; Minneapolis, MN: Fortress Press, 2007), 332–333. Though this was the common view there were those that thought otherwise, e.g. Aristotle.
  4. George Malcolm Stratton, Theophrastus and the Greek physiological psychology before Aristotle (London: G. Allen & Unwin; New York: Macmillan, 1917), 27-32.
  5. Theophrastus, De Sensu, 26
  6. William Ellery Leonard, The fragments of Empedocles (Chicago: The Open Court Publishing Company, 1908), 42-43.
  7. R. T. France, The Gospel of Matthew (The New International Commentary on the New Testament; Grand Rapids, MI: Wm. B. Eerdmans Publication Co., 2007), 6.
  8. πονηρός is translated as “unhealthy” in the NRSV and NIV; as “diseased” in the NET; and “bad” in the NASB, ESV& NLT
  9. William Arndt, Frederick W. Danker, and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago: University of Chicago Press, 2000), 744.
  10. Catherine Soanes and Angus Stevenson, eds., Concise Oxford English Dictionary (Oxford: Oxford University Press, 2004).
  11. William Arndt, Frederick W. Danker, and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago: University of Chicago Press, 2000), 104.
  12. Johannes P. Louw and Eugene Albert Nida, Greek-English Lexicon of the New Testament: Based on Semantic Domains (New York: United Bible Societies, 1996), 569.

Author: Nat R

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