I remember as a kid seeing a salt lake for the first time out in the wheatbelt. It was strange to walk across the crusted dry salt surface and taste it – yes, real salt – and to realise that this was a sort of min-desert. Nothing could grow here, and all around were the dry skeletons of dead trees. Salt, of course, is the farmer's enemy. The problem is that the wheatbelt is a very low drainage area so the rain that falls collects in shallow depressions and as it evaporates it leaves behind its natural salts. The problem of salinity is made worse by farming practices that replace native vegetation with shallow roots – with every fall of rain the water table rises and brings with it the salt stored under the topsoil. The only real solution is to replant native vegetation which has evolved to be salt-resistant, but the subterranean salt reserves are so enormous that reversing the damage of salinity could take lifetimes in the worst affected areas.
The ancient Romans knew about salinity, and used it as a weapon of war. Amongst the charming things they did to defeated populations was their practice of sowing good, arable land with salt – simply to make it useless. But they also knew salt as a vital commodity, as a substance that, in the right proportions, is essential for life – so important was salt, in the ancient economy that Roman soldiers were sometimes paid in the stuff – their wages, in salt – were called salarium- from which of course we get the word salary. Jesus' first listeners also knew that salt was necessary for life, and in the Hebrew Scriptures we read references to salt's essential nature. So for example the prophet Elisha sprinkled salt into the spring at Jericho to purify the water (2 Kings 2:21.) To eat salt with another person was a sign of loyalty, sort of a passing of the peace pipe, a breaking of bread, a sign of commonality (Numbers 18:19.) Priests strew salt on sacrifices, and seasoned incense with salt. Parents rubbed salt all over their newborn baby's body as protection against all kinds of ills (Ezekiel 16:4.)
In our modern world we know salt as a basic condiment – humble and useful, and to call somebody 'salt of the earth' is a good thing – we mean they are honest and hardworking, that they don't make a fuss but get on with the job. Salt needs to be in balance, and by itself it is useless but in the right proportion it preserves, it adds flavour, it zests things up. It changes the soil, the water, the taste of food, the function of the human body. For salt to work, it must be used with something. To be a disciple, Jesus is saying, is to be like salt, mixed right into the middle of life, adding some zest and making a difference. Being salt of the earth is a mixed metaphor, in fact – it means being humble and useful, it means being transformative and making a difference – but it carries with it a warning against getting out of control, coagulating in useless piles and poisoning the earth.
The metaphor of light seems easier. Light shows us the way, it reveals what is hidden, it is beautiful, it extends the hours of daylight so it is useful and allows us to be more productive. Like salt, of course, light is pretty pointless by itself, in fact it is invisible – the beauty that light reveals is not its own beauty but the beauty of what it shines on, and its usefulness is in what it illuminates.
So, Jesus says you are salt, and you are light. Interestingly, not 'try to be salt, or try to be light' – both of which are of course impossible instructions, just 'you are salt' and 'you are light'. As disciples – and it is disciples to whom he is speaking here, men and women who see their own lives as centred on following Jesus – as disciples, even as bumbling, accident-prone, not very brave and occasionally self-centred disciples what you actually are – is salt and light. Why? Well, it's not a compliment, but as disciples you make a difference, you transform the environment around you, and Jesus is telling us that we need to be intentional about that. There is nothing supernatural or especially spiritual about this – women and men who are sure about what they believe and who quietly order their lives around what they believe have an effect on those around them. There is a negative version of this, as well as a positive version – the advertising industry for example works on the principle that consumerist desire is infectious. Jesus is also infectious – the values of the reign of God that Jesus teaches and lives are infectious but like a grain of salt thrown into a super-concentrated solution that precipitates mass crystallisation there needs to be a catalyst and you – disciples – are it.
But there is a warning here. If we can't help but be salt, and to salt up the people around us – if we can't help but be light and to reveal things around us – then we do need to be intelligent and aware in case we do more harm than good. 'What if the salt loses its flavour?', Jesus asks – rhetorically, one hopes. It can't, of course, NaCl is NaCl, it tastes like salt. You can't literally be unsalty salt – but you can be out of balance salt, you can be the rising salinity that destroys the earth or the excess of salt that ruins the flavour of a meal and contributes to hypertension. You could be the salt of argumentativeness or rigid insistence on dogma or unattractive fundamentalism that poisons the water of the Spirit from which those around you need to drink. You could be the salt of intolerance or hypocrisy that so many people have found and been harmed by in the Church. Don't be salt like that. Be the intelligent, good-humoured salt that knows it is tastiest and most useful in small doses, that brings out the flavour in others. You get the idea? Salt when it is most useful doesn't draw attention to itself, it serves others and it subtly enhances but never overwhelms. Be humble, useful salt.
'What if the light is hidden under a container?, Jesus asks, still in rhetorical mode. The light he is thinking of is a candle, or maybe an oil lamp. We have candle-snuffers here, a little brass hood on the end of a staff that we use at the end of the service to – put the candle out. Not only does the light hidden under the container fail to illuminate anything around it – it goes out. It stops being light. Because an enclosed flame runs out of oxygen. If your light is just for yourself, then you soon find yourself in darkness. If you are a light – and as a disciple you are, because you can't help revealing something about the world around you – then you are made to shine. And you can only shine if you get yourself out there into some open space with some good clear oxygen and something to shine on. And you need fuel. You need the oxygen of the Holy Spirit and the humble candlewax of perspiration – some effort, in other words: learning, service and prayer.
One last point. These metaphors are homely, they are simple and common and inexpensive. Jesus loves metaphors like this – he talks about weeds, and wheat, and fish and oil and bread and water. Being a disciple is not rocket science, it is just about being real, and about being available. People often make a mistake about this, and they want the truth to be esoteric or mystifying and hifalutin. St Paul is struggling against something like this, in the passage we just read from his letter to the Corinthian Church. It seems they didn't think he was fancy enough. After he left Corinth people began to express scepticism about his message. They complained that he had provided no arguments and that he had no particular status in the world. The same seemed to be true of the Jesus he proclaimed.
And Paul agrees. Like the mythological pastor who comes to church one Sunday morning to find a petition doing the rounds asking for his removal because he isn't holy enough, he isn't good enough or wise enough for that congregation – so of course the pastor gets his hands on that petition and signs it. Paul agrees with all the charges levelled against him. He doesn't defend himself with skilled argument and he doesn't try to convince his fractious church at Corinth that he is better than they think, or that Jesus is more important than they think. And he tells them the Jesus that he proclaims is the crucified one, the one put to death in the most shameful way imaginable. You can't get a lower status than that, and Paul agrees: his message is 'a stumbling block to Jews and folly to Gentiles'.
But then makes this astounding claim: that God's wisdom is the reverse of human wisdom. It is what is humble and small in the world that reveals God. It is what is despised and held to be of no account in the world that most truly reflects the glory of God. The wisdom of discipleship is not about being successful, or devastatingly clever, it is not about having the right words or the best arguments, in fact, it is not even about being right. It is about being humble and available, it is about service, and it is about being in love. Be salt and light, for the world around you.